internal/mcp: meta and progress token
Meta is a struct that contains a map[string]any, and a ProgressToken field. Each Params and Result type has a Meta as a value field. Meta marshals and unmarshals specially, so the ProgressToken field becomes part of the map. The marshalling code is generalized in anticipation of every Params and Result growing a map of additional properties. Change-Id: I6d2f34270d33501c96437f24f91ef3e51d20d955 Reviewed-on: https://go-review.googlesource.com/c/tools/+/674956 Reviewed-by: Sam Thanawalla <samthanawalla@google.com> LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com> Auto-Submit: Jonathan Amsterdam <jba@google.com> Reviewed-by: Robert Findley <rfindley@google.com>
This commit is contained in:
Jonathan Amsterdam
Gopher Robot
parent
dbbdf5a181
commit
7130f0f081
12 changed files with 548 additions and 115 deletions
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@ -243,7 +243,7 @@ Types needed for the protocol are generated from the [JSON schema of the MCP spe
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These types will be included in the `mcp` package, but will be unexported unless they are needed for the user-facing API. Notably, JSON-RPC request types are elided, since they are handled by the `jsonrpc2` package and should not be observed by the user.
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For user-provided data, we use `json.RawMessage`, so that marshalling/unmarshalling can be delegated to the business logic of the client or server.
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For user-provided data, we use `json.RawMessage` or `map[string]any`, depending on the use case.
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For union types, which can't be represented in Go (specifically `Content` and `ResourceContents`), we prefer distinguished unions: struct types with fields corresponding to the union of all properties for union elements.
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@ -255,9 +255,9 @@ type ReadResourceParams struct {
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}
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type CallToolResult struct {
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Meta map[string]json.RawMessage `json:"_meta,omitempty"`
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Content []Content `json:"content"`
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IsError bool `json:"isError,omitempty"`
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Meta Meta `json:"_meta,omitempty"`
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Content []Content `json:"content"`
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IsError bool `json:"isError,omitempty"`
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}
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// Content is the wire format for content.
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@ -276,6 +276,7 @@ type Content struct {
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func NewTextContent(text string) *Content
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// etc.
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```
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The `Meta` type includes a `map[string]any` for arbitrary data, and a `ProgressToken` field.
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**Differences from mcp-go**: these types are largely similar, but our type generator flattens types rather than using struct embedding.
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@ -480,15 +481,21 @@ The server observes a client cancellation as a cancelled context.
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### Progress handling
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A caller can request progress notifications by setting the `ProgressToken` field on any request.
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A caller can request progress notifications by setting the `Meta.ProgressToken` field on any request.
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```go
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type XXXParams struct { // where XXX is each type of call
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Meta Meta
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...
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}
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type Meta struct {
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Data map[string]any
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ProgressToken any // string or int
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}
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```
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Handlers can notify their peer about progress by calling the `NotifyProgress` method. The notification is only sent if the peer requested it by providing a progress token.
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```go
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@ -616,14 +616,19 @@ func structPropertiesOf(t reflect.Type) propertyMap {
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// jsonName returns the name for f as would be used by [json.Marshal].
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// That is the name in the json struct tag, or the field name if there is no tag.
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// If f is not exported or the tag name is "-", jsonName returns "", false.
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// If f is not exported or the tag is "-", jsonName returns "", false.
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func jsonName(f reflect.StructField) (string, bool) {
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if !f.IsExported() {
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return "", false
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}
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if tag, ok := f.Tag.Lookup("json"); ok {
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if name, _, _ := strings.Cut(tag, ","); name != "" {
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return name, name != "-"
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name, _, found := strings.Cut(tag, ",")
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// "-" means omit, but "-," means the name is "-"
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if name == "-" && !found {
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return "", false
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}
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if name != "" {
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return name, true
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}
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}
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return f.Name, true
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@ -10,6 +10,7 @@ import (
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"net/url"
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"os"
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"path/filepath"
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"reflect"
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"strings"
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"testing"
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)
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@ -171,6 +172,26 @@ func TestStructInstance(t *testing.T) {
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}
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}
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func TestJSONName(t *testing.T) {
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type S struct {
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A int
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B int `json:","`
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C int `json:"-"`
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D int `json:"-,"`
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E int `json:"echo"`
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F int `json:"foxtrot,omitempty"`
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g int `json:"golf"`
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}
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want := []string{"A", "B", "", "-", "echo", "foxtrot", ""}
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tt := reflect.TypeFor[S]()
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for i := range tt.NumField() {
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got, _ := jsonName(tt.Field(i))
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if got != want[i] {
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t.Errorf("got %q, want %q", got, want[i])
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}
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}
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}
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// loadRemote loads a remote reference used in the test suite.
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func loadRemote(uri *url.URL) (*Schema, error) {
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// Anything with localhost:1234 refers to the remotes directory in the test suite repo.
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@ -162,7 +162,7 @@ func (c *Client) RemoveRoots(uris ...string) {
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// changeAndNotify is called when a feature is added or removed.
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// It calls change, which should do the work and report whether a change actually occurred.
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// If there was a change, it notifies a snapshot of the sessions.
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func (c *Client) changeAndNotify(notification string, params any, change func() bool) {
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func (c *Client) changeAndNotify(notification string, params Params, change func() bool) {
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var sessions []*ClientSession
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// Lock for the change, but not for the notification.
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c.mu.Lock()
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@ -231,8 +231,8 @@ func (cs *ClientSession) methodHandler() MethodHandler[ClientSession] {
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// getConn implements [session.getConn].
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func (cs *ClientSession) getConn() *jsonrpc2.Connection { return cs.conn }
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func (c *ClientSession) ping(ct context.Context, params *PingParams) (struct{}, error) {
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return struct{}{}, nil
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func (c *ClientSession) ping(ct context.Context, params *PingParams) (Result, error) {
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return emptyResult{}, nil
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}
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// Ping makes an MCP "ping" request to the server.
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@ -296,29 +296,21 @@ func (c *ClientSession) ReadResource(ctx context.Context, params *ReadResourcePa
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return standardCall[ReadResourceResult](ctx, c.conn, methodReadResource, params)
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}
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func (c *Client) callToolChangedHandler(ctx context.Context, s *ClientSession, params *ToolListChangedParams) (any, error) {
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func (c *Client) callToolChangedHandler(ctx context.Context, s *ClientSession, params *ToolListChangedParams) (Result, error) {
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return callNotificationHandler(ctx, c.opts.ToolListChangedHandler, s, params)
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}
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func (c *Client) callPromptChangedHandler(ctx context.Context, s *ClientSession, params *PromptListChangedParams) (any, error) {
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func (c *Client) callPromptChangedHandler(ctx context.Context, s *ClientSession, params *PromptListChangedParams) (Result, error) {
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return callNotificationHandler(ctx, c.opts.PromptListChangedHandler, s, params)
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}
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func (c *Client) callResourceChangedHandler(ctx context.Context, s *ClientSession, params *ResourceListChangedParams) (any, error) {
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func (c *Client) callResourceChangedHandler(ctx context.Context, s *ClientSession, params *ResourceListChangedParams) (Result, error) {
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return callNotificationHandler(ctx, c.opts.ResourceListChangedHandler, s, params)
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}
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func (c *Client) callLoggingHandler(ctx context.Context, cs *ClientSession, params *LoggingMessageParams) (any, error) {
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func (c *Client) callLoggingHandler(ctx context.Context, cs *ClientSession, params *LoggingMessageParams) (Result, error) {
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if h := c.opts.LoggingMessageHandler; h != nil {
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h(ctx, cs, params)
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}
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return nil, nil
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}
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func standardCall[TRes, TParams any](ctx context.Context, conn *jsonrpc2.Connection, method string, params TParams) (*TRes, error) {
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var result TRes
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if err := call(ctx, conn, method, params, &result); err != nil {
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return nil, err
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}
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return &result, nil
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}
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@ -299,13 +299,21 @@ func loadSchema(schemaFile string) (data []byte, err error) {
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func writeDecl(configName string, config typeConfig, def *jsonschema.Schema, named map[string]*bytes.Buffer) error {
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var w io.Writer = io.Discard
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if typeName := config.Name; typeName != "-" {
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var typeName string
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if typeName = config.Name; typeName != "-" {
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if typeName == "" {
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typeName = configName
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}
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if _, ok := named[typeName]; ok {
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return nil
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}
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// The JSON schema does not accurately represent the source of truth, which is typescript.
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// Every Params and Result type should have a _meta property.
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// Also, those with a progress token will turn into a struct; we want the progress token to
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// be a map item. So replace all metas.
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if strings.HasSuffix(typeName, "Params") || strings.HasSuffix(typeName, "Result") {
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def.Properties["_meta"] = metaSchema
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}
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buf := new(bytes.Buffer)
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w = buf
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named[typeName] = buf
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@ -318,6 +326,12 @@ func writeDecl(configName string, config typeConfig, def *jsonschema.Schema, nam
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return err // Better error here?
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}
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fmt.Fprintf(w, "\n")
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// Any decl with a _meta field gets a GetMeta method.
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if _, ok := def.Properties["_meta"]; ok {
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fmt.Fprintf(w, "\nfunc (x *%s) GetMeta() *Meta { return &x.Meta }", typeName)
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}
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return nil
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}
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@ -354,11 +368,7 @@ func writeType(w io.Writer, config *typeConfig, def *jsonschema.Schema, named ma
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// For types that explicitly allow additional properties, we can either
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// unmarshal them into a map[string]any, or delay unmarshalling with
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// json.RawMessage. For now, use json.RawMessage as it defers the choice.
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//
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// TODO(jba): further refine this classification of object schemas.
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// For example, the typescript "object" type, which should map to a Go "any",
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// is represented in schema.json by `{type: object, properties: {}, additionalProperties: true}`.
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// json.RawMessage. We use any.
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if def.Type == "object" && canHaveAdditionalProperties(def) && def.Properties == nil {
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w.Write([]byte("map[string]"))
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return writeType(w, nil, def.AdditionalProperties, named)
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@ -372,7 +382,7 @@ func writeType(w io.Writer, config *typeConfig, def *jsonschema.Schema, named ma
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fmt.Fprintf(w, "*Content")
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} else {
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// E.g. union types.
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fmt.Fprintf(w, "json.RawMessage")
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fmt.Fprintf(w, "any")
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}
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} else {
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switch def.Type {
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@ -398,6 +408,11 @@ func writeType(w io.Writer, config *typeConfig, def *jsonschema.Schema, named ma
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if fieldDef.Description != "" {
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fmt.Fprintf(w, "%s\n", toComment(fieldDef.Description))
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}
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if name == "_meta" {
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fmt.Fprintln(w, "\tMeta Meta `json:\"_meta,omitempty\"`")
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continue
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}
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export := exportName(name)
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fmt.Fprintf(w, "\t%s ", export)
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@ -551,6 +566,12 @@ func isStruct(s *jsonschema.Schema) bool {
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return s.Type == "object" && s.Properties != nil && !canHaveAdditionalProperties(s)
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}
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// The schema for "_meta".
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// We only need the description: the rest is a special case.
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var metaSchema = &jsonschema.Schema{
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Description: "This property is reserved by the protocol to allow clients and servers to attach additional metadata to their responses.",
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}
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// schemaJSON returns the JSON for s.
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// For debugging.
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func schemaJSON(s *jsonschema.Schema) string {
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@ -620,7 +620,7 @@ func TestMiddleware(t *testing.T) {
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// with the given prefix.
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func traceCalls[S ClientSession | ServerSession](w io.Writer, prefix string) Middleware[S] {
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return func(h MethodHandler[S]) MethodHandler[S] {
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return func(ctx context.Context, sess *S, method string, params any) (any, error) {
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return func(ctx context.Context, sess *S, method string, params Params) (Result, error) {
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fmt.Fprintf(w, "%s >%s\n", prefix, method)
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defer fmt.Fprintf(w, "%s <%s\n", prefix, method)
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return h(ctx, sess, method, params)
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201
mcp/protocol.go
201
mcp/protocol.go
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@ -29,10 +29,15 @@ type Annotations struct {
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}
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type CallToolParams struct {
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// This property is reserved by the protocol to allow clients and servers to
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// attach additional metadata to their responses.
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Meta Meta `json:"_meta,omitempty"`
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Arguments json.RawMessage `json:"arguments,omitempty"`
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Name string `json:"name"`
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}
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func (x *CallToolParams) GetMeta() *Meta { return &x.Meta }
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// The server's response to a tool call.
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//
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// Any errors that originate from the tool SHOULD be reported inside the result
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@ -44,17 +49,22 @@ type CallToolParams struct {
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// server does not support tool calls, or any other exceptional conditions,
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// should be reported as an MCP error response.
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type CallToolResult struct {
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// This result property is reserved by the protocol to allow clients and servers
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// to attach additional metadata to their responses.
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Meta map[string]json.RawMessage `json:"_meta,omitempty"`
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Content []*Content `json:"content"`
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// This property is reserved by the protocol to allow clients and servers to
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// attach additional metadata to their responses.
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Meta Meta `json:"_meta,omitempty"`
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Content []*Content `json:"content"`
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// Whether the tool call ended in an error.
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//
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// If not set, this is assumed to be false (the call was successful).
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IsError bool `json:"isError,omitempty"`
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}
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func (x *CallToolResult) GetMeta() *Meta { return &x.Meta }
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type CancelledParams struct {
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// This property is reserved by the protocol to allow clients and servers to
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// attach additional metadata to their responses.
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Meta Meta `json:"_meta,omitempty"`
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// An optional string describing the reason for the cancellation. This MAY be
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// logged or presented to the user.
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Reason string `json:"reason,omitempty"`
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@ -65,6 +75,8 @@ type CancelledParams struct {
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RequestID any `json:"requestId"`
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}
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func (x *CancelledParams) GetMeta() *Meta { return &x.Meta }
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// Capabilities a client may support. Known capabilities are defined here, in
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// this schema, but this is not a closed set: any client can define its own,
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// additional capabilities.
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@ -82,6 +94,9 @@ type ClientCapabilities struct {
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}
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type CreateMessageParams struct {
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// This property is reserved by the protocol to allow clients and servers to
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// attach additional metadata to their responses.
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Meta Meta `json:"_meta,omitempty"`
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// A request to include context from one or more MCP servers (including the
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// caller), to be attached to the prompt. The client MAY ignore this request.
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IncludeContext string `json:"includeContext,omitempty"`
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@ -103,15 +118,17 @@ type CreateMessageParams struct {
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Temperature float64 `json:"temperature,omitempty"`
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}
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func (x *CreateMessageParams) GetMeta() *Meta { return &x.Meta }
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// The client's response to a sampling/create_message request from the server.
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// The client should inform the user before returning the sampled message, to
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// allow them to inspect the response (human in the loop) and decide whether to
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// allow the server to see it.
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type CreateMessageResult struct {
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// This result property is reserved by the protocol to allow clients and servers
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// to attach additional metadata to their responses.
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Meta map[string]json.RawMessage `json:"_meta,omitempty"`
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Content *Content `json:"content"`
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// This property is reserved by the protocol to allow clients and servers to
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// attach additional metadata to their responses.
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Meta Meta `json:"_meta,omitempty"`
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Content *Content `json:"content"`
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// The name of the model that generated the message.
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Model string `json:"model"`
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Role Role `json:"role"`
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@ -119,24 +136,36 @@ type CreateMessageResult struct {
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StopReason string `json:"stopReason,omitempty"`
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}
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func (x *CreateMessageResult) GetMeta() *Meta { return &x.Meta }
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type GetPromptParams struct {
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// This property is reserved by the protocol to allow clients and servers to
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// attach additional metadata to their responses.
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Meta Meta `json:"_meta,omitempty"`
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// Arguments to use for templating the prompt.
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Arguments map[string]string `json:"arguments,omitempty"`
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// The name of the prompt or prompt template.
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Name string `json:"name"`
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}
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func (x *GetPromptParams) GetMeta() *Meta { return &x.Meta }
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// The server's response to a prompts/get request from the client.
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type GetPromptResult struct {
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// This result property is reserved by the protocol to allow clients and servers
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// to attach additional metadata to their responses.
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Meta map[string]json.RawMessage `json:"_meta,omitempty"`
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// This property is reserved by the protocol to allow clients and servers to
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// attach additional metadata to their responses.
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Meta Meta `json:"_meta,omitempty"`
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// An optional description for the prompt.
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Description string `json:"description,omitempty"`
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Messages []*PromptMessage `json:"messages"`
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}
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func (x *GetPromptResult) GetMeta() *Meta { return &x.Meta }
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type InitializeParams struct {
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// This property is reserved by the protocol to allow clients and servers to
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// attach additional metadata to their responses.
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Meta Meta `json:"_meta,omitempty"`
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Capabilities *ClientCapabilities `json:"capabilities"`
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ClientInfo *implementation `json:"clientInfo"`
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// The latest version of the Model Context Protocol that the client supports.
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@ -144,13 +173,15 @@ type InitializeParams struct {
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ProtocolVersion string `json:"protocolVersion"`
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}
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func (x *InitializeParams) GetMeta() *Meta { return &x.Meta }
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// After receiving an initialize request from the client, the server sends this
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// response.
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type InitializeResult struct {
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// This result property is reserved by the protocol to allow clients and servers
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// to attach additional metadata to their responses.
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Meta map[string]json.RawMessage `json:"_meta,omitempty"`
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Capabilities *serverCapabilities `json:"capabilities"`
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// This property is reserved by the protocol to allow clients and servers to
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// attach additional metadata to their responses.
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Meta Meta `json:"_meta,omitempty"`
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Capabilities *serverCapabilities `json:"capabilities"`
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// Instructions describing how to use the server and its features.
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//
|
||||
// This can be used by clients to improve the LLM's understanding of available
|
||||
|
|
@ -164,83 +195,108 @@ type InitializeResult struct {
|
|||
ServerInfo *implementation `json:"serverInfo"`
|
||||
}
|
||||
|
||||
func (x *InitializeResult) GetMeta() *Meta { return &x.Meta }
|
||||
|
||||
type InitializedParams struct {
|
||||
// This parameter name is reserved by MCP to allow clients and servers to attach
|
||||
// additional metadata to their notifications.
|
||||
Meta map[string]json.RawMessage `json:"_meta,omitempty"`
|
||||
// This property is reserved by the protocol to allow clients and servers to
|
||||
// attach additional metadata to their responses.
|
||||
Meta Meta `json:"_meta,omitempty"`
|
||||
}
|
||||
|
||||
func (x *InitializedParams) GetMeta() *Meta { return &x.Meta }
|
||||
|
||||
type ListPromptsParams struct {
|
||||
// This property is reserved by the protocol to allow clients and servers to
|
||||
// attach additional metadata to their responses.
|
||||
Meta Meta `json:"_meta,omitempty"`
|
||||
// An opaque token representing the current pagination position. If provided,
|
||||
// the server should return results starting after this cursor.
|
||||
Cursor string `json:"cursor,omitempty"`
|
||||
}
|
||||
|
||||
func (x *ListPromptsParams) GetMeta() *Meta { return &x.Meta }
|
||||
|
||||
// The server's response to a prompts/list request from the client.
|
||||
type ListPromptsResult struct {
|
||||
// This result property is reserved by the protocol to allow clients and servers
|
||||
// to attach additional metadata to their responses.
|
||||
Meta map[string]json.RawMessage `json:"_meta,omitempty"`
|
||||
// This property is reserved by the protocol to allow clients and servers to
|
||||
// attach additional metadata to their responses.
|
||||
Meta Meta `json:"_meta,omitempty"`
|
||||
// An opaque token representing the pagination position after the last returned
|
||||
// result. If present, there may be more results available.
|
||||
NextCursor string `json:"nextCursor,omitempty"`
|
||||
Prompts []*Prompt `json:"prompts"`
|
||||
}
|
||||
|
||||
func (x *ListPromptsResult) GetMeta() *Meta { return &x.Meta }
|
||||
|
||||
type ListResourcesParams struct {
|
||||
// This property is reserved by the protocol to allow clients and servers to
|
||||
// attach additional metadata to their responses.
|
||||
Meta Meta `json:"_meta,omitempty"`
|
||||
// An opaque token representing the current pagination position. If provided,
|
||||
// the server should return results starting after this cursor.
|
||||
Cursor string `json:"cursor,omitempty"`
|
||||
}
|
||||
|
||||
func (x *ListResourcesParams) GetMeta() *Meta { return &x.Meta }
|
||||
|
||||
// The server's response to a resources/list request from the client.
|
||||
type ListResourcesResult struct {
|
||||
// This result property is reserved by the protocol to allow clients and servers
|
||||
// to attach additional metadata to their responses.
|
||||
Meta map[string]json.RawMessage `json:"_meta,omitempty"`
|
||||
// This property is reserved by the protocol to allow clients and servers to
|
||||
// attach additional metadata to their responses.
|
||||
Meta Meta `json:"_meta,omitempty"`
|
||||
// An opaque token representing the pagination position after the last returned
|
||||
// result. If present, there may be more results available.
|
||||
NextCursor string `json:"nextCursor,omitempty"`
|
||||
Resources []*Resource `json:"resources"`
|
||||
}
|
||||
|
||||
func (x *ListResourcesResult) GetMeta() *Meta { return &x.Meta }
|
||||
|
||||
type ListRootsParams struct {
|
||||
Meta struct {
|
||||
// If specified, the caller is requesting out-of-band progress notifications for
|
||||
// this request (as represented by notifications/progress). The value of this
|
||||
// parameter is an opaque token that will be attached to any subsequent
|
||||
// notifications. The receiver is not obligated to provide these notifications.
|
||||
ProgressToken any `json:"progressToken,omitempty"`
|
||||
} `json:"_meta,omitempty"`
|
||||
// This property is reserved by the protocol to allow clients and servers to
|
||||
// attach additional metadata to their responses.
|
||||
Meta Meta `json:"_meta,omitempty"`
|
||||
}
|
||||
|
||||
func (x *ListRootsParams) GetMeta() *Meta { return &x.Meta }
|
||||
|
||||
// The client's response to a roots/list request from the server. This result
|
||||
// contains an array of Root objects, each representing a root directory or file
|
||||
// that the server can operate on.
|
||||
type ListRootsResult struct {
|
||||
// This result property is reserved by the protocol to allow clients and servers
|
||||
// to attach additional metadata to their responses.
|
||||
Meta map[string]json.RawMessage `json:"_meta,omitempty"`
|
||||
Roots []*Root `json:"roots"`
|
||||
// This property is reserved by the protocol to allow clients and servers to
|
||||
// attach additional metadata to their responses.
|
||||
Meta Meta `json:"_meta,omitempty"`
|
||||
Roots []*Root `json:"roots"`
|
||||
}
|
||||
|
||||
func (x *ListRootsResult) GetMeta() *Meta { return &x.Meta }
|
||||
|
||||
type ListToolsParams struct {
|
||||
// This property is reserved by the protocol to allow clients and servers to
|
||||
// attach additional metadata to their responses.
|
||||
Meta Meta `json:"_meta,omitempty"`
|
||||
// An opaque token representing the current pagination position. If provided,
|
||||
// the server should return results starting after this cursor.
|
||||
Cursor string `json:"cursor,omitempty"`
|
||||
}
|
||||
|
||||
func (x *ListToolsParams) GetMeta() *Meta { return &x.Meta }
|
||||
|
||||
// The server's response to a tools/list request from the client.
|
||||
type ListToolsResult struct {
|
||||
// This result property is reserved by the protocol to allow clients and servers
|
||||
// to attach additional metadata to their responses.
|
||||
Meta map[string]json.RawMessage `json:"_meta,omitempty"`
|
||||
// This property is reserved by the protocol to allow clients and servers to
|
||||
// attach additional metadata to their responses.
|
||||
Meta Meta `json:"_meta,omitempty"`
|
||||
// An opaque token representing the pagination position after the last returned
|
||||
// result. If present, there may be more results available.
|
||||
NextCursor string `json:"nextCursor,omitempty"`
|
||||
Tools []*Tool `json:"tools"`
|
||||
}
|
||||
|
||||
func (x *ListToolsResult) GetMeta() *Meta { return &x.Meta }
|
||||
|
||||
// The severity of a log message.
|
||||
//
|
||||
// These map to syslog message severities, as specified in RFC-5424:
|
||||
|
|
@ -248,6 +304,9 @@ type ListToolsResult struct {
|
|||
type LoggingLevel string
|
||||
|
||||
type LoggingMessageParams struct {
|
||||
// This property is reserved by the protocol to allow clients and servers to
|
||||
// attach additional metadata to their responses.
|
||||
Meta Meta `json:"_meta,omitempty"`
|
||||
// The data to be logged, such as a string message or an object. Any JSON
|
||||
// serializable type is allowed here.
|
||||
Data any `json:"data"`
|
||||
|
|
@ -257,6 +316,8 @@ type LoggingMessageParams struct {
|
|||
Logger string `json:"logger,omitempty"`
|
||||
}
|
||||
|
||||
func (x *LoggingMessageParams) GetMeta() *Meta { return &x.Meta }
|
||||
|
||||
// Hints to use for model selection.
|
||||
//
|
||||
// Keys not declared here are currently left unspecified by the spec and are up
|
||||
|
|
@ -310,15 +371,13 @@ type ModelPreferences struct {
|
|||
}
|
||||
|
||||
type PingParams struct {
|
||||
Meta struct {
|
||||
// If specified, the caller is requesting out-of-band progress notifications for
|
||||
// this request (as represented by notifications/progress). The value of this
|
||||
// parameter is an opaque token that will be attached to any subsequent
|
||||
// notifications. The receiver is not obligated to provide these notifications.
|
||||
ProgressToken any `json:"progressToken,omitempty"`
|
||||
} `json:"_meta,omitempty"`
|
||||
// This property is reserved by the protocol to allow clients and servers to
|
||||
// attach additional metadata to their responses.
|
||||
Meta Meta `json:"_meta,omitempty"`
|
||||
}
|
||||
|
||||
func (x *PingParams) GetMeta() *Meta { return &x.Meta }
|
||||
|
||||
// A prompt or prompt template that the server offers.
|
||||
type Prompt struct {
|
||||
// A list of arguments to use for templating the prompt.
|
||||
|
|
@ -340,11 +399,13 @@ type PromptArgument struct {
|
|||
}
|
||||
|
||||
type PromptListChangedParams struct {
|
||||
// This parameter name is reserved by MCP to allow clients and servers to attach
|
||||
// additional metadata to their notifications.
|
||||
Meta map[string]json.RawMessage `json:"_meta,omitempty"`
|
||||
// This property is reserved by the protocol to allow clients and servers to
|
||||
// attach additional metadata to their responses.
|
||||
Meta Meta `json:"_meta,omitempty"`
|
||||
}
|
||||
|
||||
func (x *PromptListChangedParams) GetMeta() *Meta { return &x.Meta }
|
||||
|
||||
// Describes a message returned as part of a prompt.
|
||||
//
|
||||
// This is similar to `SamplingMessage`, but also supports the embedding of
|
||||
|
|
@ -355,19 +416,26 @@ type PromptMessage struct {
|
|||
}
|
||||
|
||||
type ReadResourceParams struct {
|
||||
// This property is reserved by the protocol to allow clients and servers to
|
||||
// attach additional metadata to their responses.
|
||||
Meta Meta `json:"_meta,omitempty"`
|
||||
// The URI of the resource to read. The URI can use any protocol; it is up to
|
||||
// the server how to interpret it.
|
||||
URI string `json:"uri"`
|
||||
}
|
||||
|
||||
func (x *ReadResourceParams) GetMeta() *Meta { return &x.Meta }
|
||||
|
||||
// The server's response to a resources/read request from the client.
|
||||
type ReadResourceResult struct {
|
||||
// This result property is reserved by the protocol to allow clients and servers
|
||||
// to attach additional metadata to their responses.
|
||||
Meta map[string]json.RawMessage `json:"_meta,omitempty"`
|
||||
Contents *ResourceContents `json:"contents"`
|
||||
// This property is reserved by the protocol to allow clients and servers to
|
||||
// attach additional metadata to their responses.
|
||||
Meta Meta `json:"_meta,omitempty"`
|
||||
Contents *ResourceContents `json:"contents"`
|
||||
}
|
||||
|
||||
func (x *ReadResourceResult) GetMeta() *Meta { return &x.Meta }
|
||||
|
||||
// A known resource that the server is capable of reading.
|
||||
type Resource struct {
|
||||
// Optional annotations for the client.
|
||||
|
|
@ -394,11 +462,13 @@ type Resource struct {
|
|||
}
|
||||
|
||||
type ResourceListChangedParams struct {
|
||||
// This parameter name is reserved by MCP to allow clients and servers to attach
|
||||
// additional metadata to their notifications.
|
||||
Meta map[string]json.RawMessage `json:"_meta,omitempty"`
|
||||
// This property is reserved by the protocol to allow clients and servers to
|
||||
// attach additional metadata to their responses.
|
||||
Meta Meta `json:"_meta,omitempty"`
|
||||
}
|
||||
|
||||
func (x *ResourceListChangedParams) GetMeta() *Meta { return &x.Meta }
|
||||
|
||||
// The sender or recipient of messages and data in a conversation.
|
||||
type Role string
|
||||
|
||||
|
|
@ -415,11 +485,13 @@ type Root struct {
|
|||
}
|
||||
|
||||
type RootsListChangedParams struct {
|
||||
// This parameter name is reserved by MCP to allow clients and servers to attach
|
||||
// additional metadata to their notifications.
|
||||
Meta map[string]json.RawMessage `json:"_meta,omitempty"`
|
||||
// This property is reserved by the protocol to allow clients and servers to
|
||||
// attach additional metadata to their responses.
|
||||
Meta Meta `json:"_meta,omitempty"`
|
||||
}
|
||||
|
||||
func (x *RootsListChangedParams) GetMeta() *Meta { return &x.Meta }
|
||||
|
||||
// Present if the client supports sampling from an LLM.
|
||||
type SamplingCapabilities struct {
|
||||
}
|
||||
|
|
@ -431,12 +503,17 @@ type SamplingMessage struct {
|
|||
}
|
||||
|
||||
type SetLevelParams struct {
|
||||
// This property is reserved by the protocol to allow clients and servers to
|
||||
// attach additional metadata to their responses.
|
||||
Meta Meta `json:"_meta,omitempty"`
|
||||
// The level of logging that the client wants to receive from the server. The
|
||||
// server should send all logs at this level and higher (i.e., more severe) to
|
||||
// the client as notifications/message.
|
||||
Level LoggingLevel `json:"level"`
|
||||
}
|
||||
|
||||
func (x *SetLevelParams) GetMeta() *Meta { return &x.Meta }
|
||||
|
||||
// Definition for a tool the client can call.
|
||||
type Tool struct {
|
||||
// Optional additional tool information.
|
||||
|
|
@ -490,11 +567,13 @@ type ToolAnnotations struct {
|
|||
}
|
||||
|
||||
type ToolListChangedParams struct {
|
||||
// This parameter name is reserved by MCP to allow clients and servers to attach
|
||||
// additional metadata to their notifications.
|
||||
Meta map[string]json.RawMessage `json:"_meta,omitempty"`
|
||||
// This property is reserved by the protocol to allow clients and servers to
|
||||
// attach additional metadata to their responses.
|
||||
Meta Meta `json:"_meta,omitempty"`
|
||||
}
|
||||
|
||||
func (x *ToolListChangedParams) GetMeta() *Meta { return &x.Meta }
|
||||
|
||||
// Describes the name and version of an MCP implementation.
|
||||
type implementation struct {
|
||||
Name string `json:"name"`
|
||||
|
|
|
|||
|
|
@ -157,7 +157,7 @@ func (s *Server) RemoveResources(uris ...string) {
|
|||
// changeAndNotify is called when a feature is added or removed.
|
||||
// It calls change, which should do the work and report whether a change actually occurred.
|
||||
// If there was a change, it notifies a snapshot of the sessions.
|
||||
func (s *Server) changeAndNotify(notification string, params any, change func() bool) {
|
||||
func (s *Server) changeAndNotify(notification string, params Params, change func() bool) {
|
||||
var sessions []*ServerSession
|
||||
// Lock for the change, but not for the notification.
|
||||
s.mu.Lock()
|
||||
|
|
@ -358,11 +358,11 @@ func (s *Server) Connect(ctx context.Context, t Transport) (*ServerSession, erro
|
|||
return connect(ctx, t, s)
|
||||
}
|
||||
|
||||
func (s *Server) callInitializedHandler(ctx context.Context, ss *ServerSession, params *InitializedParams) (any, error) {
|
||||
func (s *Server) callInitializedHandler(ctx context.Context, ss *ServerSession, params *InitializedParams) (Result, error) {
|
||||
return callNotificationHandler(ctx, s.opts.InitializedHandler, ss, params)
|
||||
}
|
||||
|
||||
func (s *Server) callRootsListChangedHandler(ctx context.Context, ss *ServerSession, params *RootsListChangedParams) (any, error) {
|
||||
func (s *Server) callRootsListChangedHandler(ctx context.Context, ss *ServerSession, params *RootsListChangedParams) (Result, error) {
|
||||
return callNotificationHandler(ctx, s.opts.RootsListChangedHandler, ss, params)
|
||||
}
|
||||
|
||||
|
|
@ -519,15 +519,15 @@ func (ss *ServerSession) initialize(ctx context.Context, params *InitializeParam
|
|||
}, nil
|
||||
}
|
||||
|
||||
func (ss *ServerSession) ping(context.Context, *PingParams) (struct{}, error) {
|
||||
return struct{}{}, nil
|
||||
func (ss *ServerSession) ping(context.Context, *PingParams) (Result, error) {
|
||||
return emptyResult{}, nil
|
||||
}
|
||||
|
||||
func (ss *ServerSession) setLevel(_ context.Context, params *SetLevelParams) (struct{}, error) {
|
||||
func (ss *ServerSession) setLevel(_ context.Context, params *SetLevelParams) (Result, error) {
|
||||
ss.mu.Lock()
|
||||
defer ss.mu.Unlock()
|
||||
ss.logLevel = params.Level
|
||||
return struct{}{}, nil
|
||||
return emptyResult{}, nil
|
||||
}
|
||||
|
||||
// Close performs a graceful shutdown of the connection, preventing new
|
||||
|
|
|
|||
|
|
@ -14,6 +14,7 @@ import (
|
|||
"encoding/json"
|
||||
"fmt"
|
||||
"log"
|
||||
"reflect"
|
||||
"slices"
|
||||
"time"
|
||||
|
||||
|
|
@ -21,12 +22,10 @@ import (
|
|||
)
|
||||
|
||||
// A MethodHandler handles MCP messages.
|
||||
// The params argument is an XXXParams struct pointer, such as *GetPromptParams.
|
||||
// For methods, a MethodHandler must return either an XXResult struct pointer and a nil error, or
|
||||
// nil with a non-nil error.
|
||||
// For notifications, a MethodHandler must return nil, nil.
|
||||
// For methods, exactly one of the return values must be nil.
|
||||
// For notifications, both must be nil.
|
||||
type MethodHandler[S ClientSession | ServerSession] func(
|
||||
ctx context.Context, _ *S, method string, params any) (result any, err error)
|
||||
ctx context.Context, _ *S, method string, params Params) (result Result, err error)
|
||||
|
||||
// Middleware is a function from MethodHandlers to MethodHandlers.
|
||||
type Middleware[S ClientSession | ServerSession] func(MethodHandler[S]) MethodHandler[S]
|
||||
|
|
@ -56,7 +55,7 @@ func toSession[S ClientSession | ServerSession](sess *S) session[S] {
|
|||
}
|
||||
|
||||
// defaultMethodHandler is the initial MethodHandler for servers and clients, before being wrapped by middleware.
|
||||
func defaultMethodHandler[S ClientSession | ServerSession](ctx context.Context, sess *S, method string, params any) (any, error) {
|
||||
func defaultMethodHandler[S ClientSession | ServerSession](ctx context.Context, sess *S, method string, params Params) (Result, error) {
|
||||
info, ok := toSession(sess).methodInfos()[method]
|
||||
if !ok {
|
||||
// This can be called from user code, with an arbitrary value for method.
|
||||
|
|
@ -87,7 +86,7 @@ func handleRequest[S ClientSession | ServerSession](ctx context.Context, req *js
|
|||
// methodInfo is information about invoking a method.
|
||||
type methodInfo[TSession ClientSession | ServerSession] struct {
|
||||
// unmarshal params from the wire into an XXXParams struct
|
||||
unmarshalParams func(json.RawMessage) (any, error)
|
||||
unmarshalParams func(json.RawMessage) (Params, error)
|
||||
// run the code for the method
|
||||
handleMethod MethodHandler[TSession]
|
||||
}
|
||||
|
|
@ -99,40 +98,40 @@ type methodInfo[TSession ClientSession | ServerSession] struct {
|
|||
// - R: results
|
||||
|
||||
// A typedMethodHandler is like a MethodHandler, but with type information.
|
||||
type typedMethodHandler[S, P, R any] func(context.Context, *S, P) (R, error)
|
||||
type typedMethodHandler[S any, P Params, R Result] func(context.Context, *S, P) (R, error)
|
||||
|
||||
// newMethodInfo creates a methodInfo from a typedMethodHandler.
|
||||
func newMethodInfo[S ClientSession | ServerSession, P, R any](d typedMethodHandler[S, P, R]) methodInfo[S] {
|
||||
func newMethodInfo[S ClientSession | ServerSession, P Params, R Result](d typedMethodHandler[S, P, R]) methodInfo[S] {
|
||||
return methodInfo[S]{
|
||||
unmarshalParams: func(m json.RawMessage) (any, error) {
|
||||
unmarshalParams: func(m json.RawMessage) (Params, error) {
|
||||
var p P
|
||||
if err := json.Unmarshal(m, &p); err != nil {
|
||||
return nil, fmt.Errorf("unmarshaling %q into a %T: %w", m, p, err)
|
||||
}
|
||||
return p, nil
|
||||
},
|
||||
handleMethod: func(ctx context.Context, ss *S, _ string, params any) (any, error) {
|
||||
handleMethod: func(ctx context.Context, ss *S, _ string, params Params) (Result, error) {
|
||||
return d(ctx, ss, params.(P))
|
||||
},
|
||||
}
|
||||
}
|
||||
|
||||
// serverMethod is glue for creating a typedMethodHandler from a method on Server.
|
||||
func serverMethod[P, R any](f func(*Server, context.Context, *ServerSession, P) (R, error)) typedMethodHandler[ServerSession, P, R] {
|
||||
func serverMethod[P Params, R Result](f func(*Server, context.Context, *ServerSession, P) (R, error)) typedMethodHandler[ServerSession, P, R] {
|
||||
return func(ctx context.Context, ss *ServerSession, p P) (R, error) {
|
||||
return f(ss.server, ctx, ss, p)
|
||||
}
|
||||
}
|
||||
|
||||
// clientMethod is glue for creating a typedMethodHandler from a method on Server.
|
||||
func clientMethod[P, R any](f func(*Client, context.Context, *ClientSession, P) (R, error)) typedMethodHandler[ClientSession, P, R] {
|
||||
func clientMethod[P Params, R Result](f func(*Client, context.Context, *ClientSession, P) (R, error)) typedMethodHandler[ClientSession, P, R] {
|
||||
return func(ctx context.Context, cs *ClientSession, p P) (R, error) {
|
||||
return f(cs.client, ctx, cs, p)
|
||||
}
|
||||
}
|
||||
|
||||
// sessionMethod is glue for creating a typedMethodHandler from a method on ServerSession.
|
||||
func sessionMethod[S ClientSession | ServerSession, P, R any](f func(*S, context.Context, P) (R, error)) typedMethodHandler[S, P, R] {
|
||||
func sessionMethod[S ClientSession | ServerSession, P Params, R Result](f func(*S, context.Context, P) (R, error)) typedMethodHandler[S, P, R] {
|
||||
return func(ctx context.Context, sess *S, p P) (R, error) {
|
||||
return f(sess, ctx, p)
|
||||
}
|
||||
|
|
@ -151,7 +150,7 @@ const (
|
|||
CodeUnsupportedMethod = -31001
|
||||
)
|
||||
|
||||
func callNotificationHandler[S ClientSession | ServerSession, P any](ctx context.Context, h func(context.Context, *S, *P), sess *S, params *P) (any, error) {
|
||||
func callNotificationHandler[S ClientSession | ServerSession, P any](ctx context.Context, h func(context.Context, *S, *P), sess *S, params *P) (Result, error) {
|
||||
if h != nil {
|
||||
h(ctx, sess, params)
|
||||
}
|
||||
|
|
@ -160,7 +159,7 @@ func callNotificationHandler[S ClientSession | ServerSession, P any](ctx context
|
|||
|
||||
// notifySessions calls Notify on all the sessions.
|
||||
// Should be called on a copy of the peer sessions.
|
||||
func notifySessions[S ClientSession | ServerSession](sessions []*S, method string, params any) {
|
||||
func notifySessions[S ClientSession | ServerSession](sessions []*S, method string, params Params) {
|
||||
if sessions == nil {
|
||||
return
|
||||
}
|
||||
|
|
@ -174,3 +173,57 @@ func notifySessions[S ClientSession | ServerSession](sessions []*S, method strin
|
|||
}
|
||||
}
|
||||
}
|
||||
|
||||
func standardCall[TRes, TParams any](ctx context.Context, conn *jsonrpc2.Connection, method string, params TParams) (*TRes, error) {
|
||||
var result TRes
|
||||
if err := call(ctx, conn, method, params, &result); err != nil {
|
||||
return nil, err
|
||||
}
|
||||
return &result, nil
|
||||
}
|
||||
|
||||
type Meta struct {
|
||||
Data map[string]any `json:",omitempty"`
|
||||
// For params, the progress token can be nil, a string or an integer.
|
||||
// It should be nil for results.
|
||||
ProgressToken any `json:"progressToken,omitempty"`
|
||||
}
|
||||
|
||||
type metaSansMethods Meta // avoid infinite recursion during marshaling
|
||||
|
||||
func (m Meta) MarshalJSON() ([]byte, error) {
|
||||
if p := m.ProgressToken; p != nil {
|
||||
if k := reflect.ValueOf(p).Kind(); k != reflect.Int && k != reflect.String {
|
||||
return nil, fmt.Errorf("bad type %T for Meta.ProgressToken: must be int or string", p)
|
||||
}
|
||||
}
|
||||
// If ProgressToken is nil, accept Data["progressToken"]. We can't call marshalStructWithMap
|
||||
// in that case because it will complain about duplicate fields. (We'd have to
|
||||
// make it much smarter to avoid that; not worth it.)
|
||||
if m.ProgressToken == nil {
|
||||
return json.Marshal(m.Data)
|
||||
}
|
||||
return marshalStructWithMap((*metaSansMethods)(&m), "Data")
|
||||
}
|
||||
|
||||
func (m *Meta) UnmarshalJSON(data []byte) error {
|
||||
return unmarshalStructWithMap(data, (*metaSansMethods)(m), "Data")
|
||||
}
|
||||
|
||||
// Params is a parameter (input) type for an MCP call or notification.
|
||||
type Params interface {
|
||||
// Returns a pointer to the params's Meta field.
|
||||
GetMeta() *Meta
|
||||
}
|
||||
|
||||
// Result is a result of an MCP call.
|
||||
type Result interface {
|
||||
// Returns a pointer to the result's Meta field.
|
||||
GetMeta() *Meta
|
||||
}
|
||||
|
||||
// emptyResult is returned by methods that have no result, like ping.
|
||||
// Those methods cannot return nil, because jsonrpc2 cannot handle nils.
|
||||
type emptyResult struct{}
|
||||
|
||||
func (emptyResult) GetMeta() *Meta { panic("should never be called") }
|
||||
|
|
|
|||
70
mcp/shared_test.go
Normal file
70
mcp/shared_test.go
Normal file
|
|
@ -0,0 +1,70 @@
|
|||
// Copyright 2025 The Go MCP SDK Authors. All rights reserved.
|
||||
// Use of this source code is governed by an MIT-style
|
||||
// license that can be found in the LICENSE file.
|
||||
|
||||
package mcp
|
||||
|
||||
import (
|
||||
"encoding/json"
|
||||
"strings"
|
||||
"testing"
|
||||
|
||||
"github.com/google/go-cmp/cmp"
|
||||
)
|
||||
|
||||
func TestMetaMarshal(t *testing.T) {
|
||||
// Verify that Meta values round-trip.
|
||||
for _, meta := range []Meta{
|
||||
{Data: nil, ProgressToken: nil},
|
||||
{Data: nil, ProgressToken: "p"},
|
||||
{Data: map[string]any{"d": true}, ProgressToken: nil},
|
||||
{Data: map[string]any{"d": true}, ProgressToken: "p"},
|
||||
} {
|
||||
got := roundTrip(t, meta)
|
||||
if !cmp.Equal(got, meta) {
|
||||
t.Errorf("\ngot %#v\nwant %#v", got, meta)
|
||||
}
|
||||
}
|
||||
|
||||
// Check errors.
|
||||
for _, tt := range []struct {
|
||||
meta Meta
|
||||
want string
|
||||
}{
|
||||
{
|
||||
Meta{Data: map[string]any{"progressToken": "p"}, ProgressToken: 1},
|
||||
"duplicate",
|
||||
},
|
||||
{
|
||||
Meta{ProgressToken: true},
|
||||
"bad type",
|
||||
},
|
||||
} {
|
||||
_, err := json.Marshal(tt.meta)
|
||||
if err == nil || !strings.Contains(err.Error(), tt.want) {
|
||||
t.Errorf("%+v: got %v, want error containing %q", tt.meta, err, tt.want)
|
||||
}
|
||||
}
|
||||
|
||||
// Accept progressToken in map if the field is nil.
|
||||
// It will unmarshal by populating ProgressToken.
|
||||
meta := Meta{Data: map[string]any{"progressToken": "p"}}
|
||||
got := roundTrip(t, meta)
|
||||
want := Meta{ProgressToken: "p"}
|
||||
if !cmp.Equal(got, want) {
|
||||
t.Errorf("got %+v, want %+v", got, want)
|
||||
}
|
||||
}
|
||||
|
||||
func roundTrip[T any](t *testing.T, v T) T {
|
||||
t.Helper()
|
||||
bytes, err := json.Marshal(v)
|
||||
if err != nil {
|
||||
t.Fatal(err)
|
||||
}
|
||||
var res T
|
||||
if err := json.Unmarshal(bytes, &res); err != nil {
|
||||
t.Fatal(err)
|
||||
}
|
||||
return res
|
||||
}
|
||||
137
mcp/util.go
137
mcp/util.go
|
|
@ -6,6 +6,11 @@ package mcp
|
|||
|
||||
import (
|
||||
"crypto/rand"
|
||||
"encoding/json"
|
||||
"fmt"
|
||||
"reflect"
|
||||
"strings"
|
||||
"sync"
|
||||
)
|
||||
|
||||
func assert(cond bool, msg string) {
|
||||
|
|
@ -27,3 +32,135 @@ func randText() string {
|
|||
}
|
||||
return string(src)
|
||||
}
|
||||
|
||||
// marshalStructWithMap marshals its first argument to JSON, treating the field named
|
||||
// mapField as an embedded map. The first argument must be a pointer to
|
||||
// a struct. The underlying type of mapField must be a map[string]any, and it must have
|
||||
// an "omitempty" json tag.
|
||||
//
|
||||
// For example, given this struct:
|
||||
//
|
||||
// type S struct {
|
||||
// A int
|
||||
// Extra map[string] any `json:,omitempty`
|
||||
// }
|
||||
//
|
||||
// and this value:
|
||||
//
|
||||
// s := S{A: 1, Extra: map[string]any{"B": 2}}
|
||||
//
|
||||
// the call marshalJSONWithMap(s, "Extra") would return
|
||||
//
|
||||
// {"A": 1, "B": 2}
|
||||
//
|
||||
// It is an error if the map contains the same key as another struct field's
|
||||
// JSON name.
|
||||
//
|
||||
// marshalStructWithMap calls json.Marshal on a value of type T, so T must not
|
||||
// have a MarshalJSON method that calls this function, on pain of infinite regress.
|
||||
//
|
||||
// TODO: avoid this restriction on T by forcing it to marshal in a default way.
|
||||
// See https://go.dev/play/p/EgXKJHxEx_R.
|
||||
func marshalStructWithMap[T any](s *T, mapField string) ([]byte, error) {
|
||||
// Marshal the struct and the map separately, and concatenate the bytes.
|
||||
// This strategy is dramatically less complicated than
|
||||
// constructing a synthetic struct or map with the combined keys.
|
||||
if s == nil {
|
||||
return []byte("null"), nil
|
||||
}
|
||||
s2 := *s
|
||||
vMapField := reflect.ValueOf(&s2).Elem().FieldByName(mapField)
|
||||
mapVal := vMapField.Interface().(map[string]any)
|
||||
|
||||
// Check for duplicates.
|
||||
names := jsonNames(reflect.TypeFor[T]())
|
||||
for key := range mapVal {
|
||||
if names[key] {
|
||||
return nil, fmt.Errorf("map key %q duplicates struct field", key)
|
||||
}
|
||||
}
|
||||
|
||||
// Clear the map field, relying on the omitempty tag to omit it.
|
||||
vMapField.Set(reflect.Zero(vMapField.Type()))
|
||||
structBytes, err := json.Marshal(s2)
|
||||
if err != nil {
|
||||
return nil, fmt.Errorf("marshalStructWithMap(%+v): %w", s, err)
|
||||
}
|
||||
if len(mapVal) == 0 {
|
||||
return structBytes, nil
|
||||
}
|
||||
mapBytes, err := json.Marshal(mapVal)
|
||||
if err != nil {
|
||||
return nil, err
|
||||
}
|
||||
if len(structBytes) == 2 { // must be "{}"
|
||||
return mapBytes, nil
|
||||
}
|
||||
// "{X}" + "{Y}" => "{X,Y}"
|
||||
res := append(structBytes[:len(structBytes)-1], ',')
|
||||
res = append(res, mapBytes[1:]...)
|
||||
return res, nil
|
||||
}
|
||||
|
||||
// unmarshalStructWithMap is the inverse of marshalStructWithMap.
|
||||
// T has the same restrictions as in that function.
|
||||
func unmarshalStructWithMap[T any](data []byte, v *T, mapField string) error {
|
||||
// Unmarshal into the struct, ignoring unknown fields.
|
||||
if err := json.Unmarshal(data, v); err != nil {
|
||||
return err
|
||||
}
|
||||
// Unmarshal into the map.
|
||||
m := map[string]any{}
|
||||
if err := json.Unmarshal(data, &m); err != nil {
|
||||
return err
|
||||
}
|
||||
// Delete from the map the fields of the struct.
|
||||
for n := range jsonNames(reflect.TypeFor[T]()) {
|
||||
delete(m, n)
|
||||
}
|
||||
if len(m) != 0 {
|
||||
reflect.ValueOf(v).Elem().FieldByName(mapField).Set(reflect.ValueOf(m))
|
||||
}
|
||||
return nil
|
||||
}
|
||||
|
||||
var jsonNamesMap sync.Map // from reflect.Type to map[string]bool
|
||||
|
||||
// jsonNames returns the set of JSON object keys that t will marshal into.
|
||||
// t must be a struct type.
|
||||
func jsonNames(t reflect.Type) map[string]bool {
|
||||
// Lock not necessary: at worst we'll duplicate work.
|
||||
if val, ok := jsonNamesMap.Load(t); ok {
|
||||
return val.(map[string]bool)
|
||||
}
|
||||
m := map[string]bool{}
|
||||
for i := range t.NumField() {
|
||||
if n, ok := jsonName(t.Field(i)); ok {
|
||||
m[n] = true
|
||||
}
|
||||
}
|
||||
jsonNamesMap.Store(t, m)
|
||||
return m
|
||||
}
|
||||
|
||||
// jsonName returns the name for f as would be used by [json.Marshal].
|
||||
// That is the name in the json struct tag, or the field name if there is no tag.
|
||||
// If f is not exported or the tag is "-", jsonName returns "", false.
|
||||
//
|
||||
// Copied from jsonschema/validate.go.
|
||||
func jsonName(f reflect.StructField) (string, bool) {
|
||||
if !f.IsExported() {
|
||||
return "", false
|
||||
}
|
||||
if tag, ok := f.Tag.Lookup("json"); ok {
|
||||
name, _, found := strings.Cut(tag, ",")
|
||||
// "-" means omit, but "-," means the name is "-"
|
||||
if name == "-" && !found {
|
||||
return "", false
|
||||
}
|
||||
if name != "" {
|
||||
return name, true
|
||||
}
|
||||
}
|
||||
return f.Name, true
|
||||
}
|
||||
|
|
|
|||
48
mcp/util_test.go
Normal file
48
mcp/util_test.go
Normal file
|
|
@ -0,0 +1,48 @@
|
|||
// Copyright 2025 The Go MCP SDK Authors. All rights reserved.
|
||||
// Use of this source code is governed by an MIT-style
|
||||
// license that can be found in the LICENSE file.
|
||||
|
||||
package mcp
|
||||
|
||||
import (
|
||||
"strings"
|
||||
"testing"
|
||||
|
||||
"github.com/google/go-cmp/cmp"
|
||||
"github.com/google/go-cmp/cmp/cmpopts"
|
||||
)
|
||||
|
||||
func TestMarshalStructWithMap(t *testing.T) {
|
||||
type S struct {
|
||||
A int
|
||||
B string `json:"b,omitempty"`
|
||||
u bool
|
||||
M map[string]any `json:",omitempty"`
|
||||
}
|
||||
t.Run("basic", func(t *testing.T) {
|
||||
s := S{A: 1, B: "two", M: map[string]any{"!@#": true}}
|
||||
got, err := marshalStructWithMap(&s, "M")
|
||||
if err != nil {
|
||||
t.Fatal(err)
|
||||
}
|
||||
want := `{"A":1,"b":"two","!@#":true}`
|
||||
if g := string(got); g != want {
|
||||
t.Errorf("\ngot %s\nwant %s", g, want)
|
||||
}
|
||||
|
||||
var un S
|
||||
if err := unmarshalStructWithMap(got, &un, "M"); err != nil {
|
||||
t.Fatal(err)
|
||||
}
|
||||
if diff := cmp.Diff(s, un, cmpopts.IgnoreUnexported(S{})); diff != "" {
|
||||
t.Errorf("mismatch (-want, +got):\n%s", diff)
|
||||
}
|
||||
})
|
||||
t.Run("duplicate", func(t *testing.T) {
|
||||
s := S{A: 1, B: "two", M: map[string]any{"b": "dup"}}
|
||||
_, err := marshalStructWithMap(&s, "M")
|
||||
if err == nil || !strings.Contains(err.Error(), "duplicate") {
|
||||
t.Errorf("got %v, want error with 'duplicate'", err)
|
||||
}
|
||||
})
|
||||
}
|
||||
Loading…
Reference in a new issue