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generate.go: remove

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Remove the code generator. It has served its purpose.
From now on, we will modify protocol.go directly.
This commit is contained in:
Jonathan Amsterdam 2025-06-23 20:16:40 -04:00 • committed by GitHub
commit 9305d6994f
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674
mcp/generate.go
View file

@ -1,674 +0,0 @@
// 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.
//go:build ignore
// This script generates protocol definitions in protocol.go from the MCP spec.
//
// Only the set of declarations configured by the [declarations] value are
// generated.
package main
import (
"bytes"
"encoding/json"
"flag"
"fmt"
"go/format"
"io"
"log"
"maps"
"net/http"
"os"
"reflect"
"regexp"
"slices"
"strings"
"github.com/modelcontextprotocol/go-sdk/internal/util"
"github.com/modelcontextprotocol/go-sdk/jsonschema"
)
var schemaFile = flag.String("schema_file", "", "if set, use this file as the persistent schema file")
// A typeConfig defines a rewrite to perform to a (possibly nested) struct
// field. In some cases, we may want to use an external type for the nested
// struct field. In others, we may want to extract the type definition to a
// name.
type typeConfig struct {
Name string // declaration name for the type
TypeParams [][2]string // formatted type parameter list ({name, constraint}), if any
Substitute string // type definition to substitute
Fields config // individual field configuration, or nil
}
type config map[string]*typeConfig
// declarations configures the set of declarations to write.
//
// Top level declarations are created unless configured with Name=="-",
// in which case they are discarded, though their fields may be
// extracted to types if they have a nested field configuration.
// If Name == "", the map key is used as the type name.
var declarations = config{
"Annotations": {},
"CallToolRequest": {
Name: "-",
Fields: config{
"Params": {
Name: "CallToolParams",
Fields: config{
"Arguments": {Substitute: "any"},
},
},
},
},
"CallToolResult": {},
"CancelledNotification": {
Name: "-",
Fields: config{"Params": {Name: "CancelledParams"}},
},
"ClientCapabilities": {
Fields: config{"Sampling": {Name: "SamplingCapabilities"}},
},
"CreateMessageRequest": {
Name: "-",
Fields: config{"Params": {Name: "CreateMessageParams"}},
},
"CreateMessageResult": {},
"GetPromptRequest": {
Name: "-",
Fields: config{"Params": {Name: "GetPromptParams"}},
},
"GetPromptResult": {},
"Implementation": {Name: "implementation"},
"InitializeRequest": {
Name: "-",
Fields: config{"Params": {Name: "InitializeParams"}},
},
"InitializeResult": {Name: "InitializeResult"},
"InitializedNotification": {
Name: "-",
Fields: config{"Params": {Name: "InitializedParams"}},
},
"ListPromptsRequest": {
Name: "-",
Fields: config{"Params": {Name: "ListPromptsParams"}},
},
"ListPromptsResult": {},
"ListResourcesRequest": {
Name: "-",
Fields: config{"Params": {Name: "ListResourcesParams"}},
},
"ListResourcesResult": {},
"ListResourceTemplatesRequest": {
Name: "-",
Fields: config{"Params": {Name: "ListResourceTemplatesParams"}},
},
"ListResourceTemplatesResult": {},
"ListRootsRequest": {
Name: "-",
Fields: config{"Params": {Name: "ListRootsParams"}},
},
"ListRootsResult": {},
"ListToolsRequest": {
Name: "-",
Fields: config{"Params": {Name: "ListToolsParams"}},
},
"ListToolsResult": {},
"loggingCapabilities": {Substitute: "struct{}"},
"LoggingLevel": {},
"LoggingMessageNotification": {
Name: "-",
Fields: config{
"Params": {
Name: "LoggingMessageParams",
Fields: config{"Data": {Substitute: "any"}},
},
},
},
"ModelHint": {},
"ModelPreferences": {},
"PingRequest": {
Name: "-",
Fields: config{"Params": {Name: "PingParams"}},
},
"Prompt": {},
"PromptMessage": {},
"PromptArgument": {},
"PromptListChangedNotification": {
Name: "-",
Fields: config{"Params": {Name: "PromptListChangedParams"}},
},
"ProgressNotification": {
Name: "-",
Fields: config{"Params": {Name: "ProgressNotificationParams"}},
},
"ProgressToken": {Name: "-", Substitute: "any"}, // null|number|string
"RequestId": {Name: "-", Substitute: "any"}, // null|number|string
"ReadResourceRequest": {
Name: "-",
Fields: config{"Params": {Name: "ReadResourceParams"}},
},
"ReadResourceResult": {
Fields: config{"Contents": {Substitute: "[]*ResourceContents"}},
},
"Resource": {},
"ResourceListChangedNotification": {
Name: "-",
Fields: config{"Params": {Name: "ResourceListChangedParams"}},
},
"ResourceTemplate": {},
"ResourceTemplateListChangedNotification": {
Name: "-",
Fields: config{"Params": {Name: "ResourceTemplateListChangedParams"}},
},
"Role": {},
"Root": {},
"RootsListChangedNotification": {
Name: "-",
Fields: config{"Params": {Name: "RootsListChangedParams"}},
},
"SamplingCapabilities": {Substitute: "struct{}"},
"SamplingMessage": {},
"ServerCapabilities": {
Name: "serverCapabilities",
Fields: config{
"Prompts": {Name: "promptCapabilities"},
"Resources": {Name: "resourceCapabilities"},
"Tools": {Name: "toolCapabilities"},
"Logging": {Name: "loggingCapabilities"},
},
},
"SetLevelRequest": {
Name: "-",
Fields: config{"Params": {Name: "SetLevelParams"}},
},
"Tool": {
Fields: config{"InputSchema": {Substitute: "*jsonschema.Schema"}},
},
"ToolAnnotations": {},
"ToolListChangedNotification": {
Name: "-",
Fields: config{"Params": {Name: "ToolListChangedParams"}},
},
}
func main() {
flag.Parse()
// Load and unmarshal the schema.
data, err := loadSchema(*schemaFile)
if err != nil {
log.Fatal(err)
}
schema := new(jsonschema.Schema)
if err := json.Unmarshal(data, &schema); err != nil {
log.Fatal(err)
}
// Resolve the schema so we have the referents of all the Refs.
if _, err := schema.Resolve(nil); err != nil {
log.Fatal(err)
}
// Collect named types. Since we may create new type definitions while
// writing types, we collect definitions and concatenate them later. This
// also allows us to sort.
named := make(map[string]*bytes.Buffer)
for name, def := range util.Sorted(schema.Definitions) {
config := declarations[name]
if config == nil {
continue
}
if err := writeDecl(name, *config, def, named); err != nil {
log.Fatal(err)
}
}
buf := new(bytes.Buffer)
fmt.Fprintf(buf, `
// 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.
// Code generated by generate.go. DO NOT EDIT.
package mcp
import (
"github.com/modelcontextprotocol/go-sdk/jsonschema"
)
`)
// Write out types.
for _, b := range util.Sorted(named) {
fmt.Fprintln(buf)
fmt.Fprint(buf, b.String())
}
// Write out method names.
fmt.Fprintln(buf, `const (`)
for _, name := range slices.Sorted(maps.Keys(schema.Definitions)) {
prefix := "method"
method, found := strings.CutSuffix(name, "Request")
if !found {
prefix = "notification"
method, found = strings.CutSuffix(name, "Notification")
}
if found {
if ms, ok := schema.Definitions[name].Properties["method"]; ok {
if c := ms.Const; c != nil {
fmt.Fprintf(buf, "%s%s = %q\n", prefix, method, *c)
}
}
}
}
fmt.Fprintln(buf, `)`)
formatted, err := format.Source(buf.Bytes())
if err != nil {
log.Println(buf.String())
log.Fatalf("failed to format: %v", err)
}
if err := os.WriteFile("protocol.go", formatted, 0666); err != nil {
log.Fatalf("failed to write protocol.go: %v", err)
}
}
func loadSchema(schemaFile string) (data []byte, err error) {
const schemaURL = "https://raw.githubusercontent.com/modelcontextprotocol/modelcontextprotocol/refs/heads/main/schema/2025-03-26/schema.json"
if schemaFile != "" {
data, err = os.ReadFile(schemaFile)
if os.IsNotExist(err) {
data = nil
} else if err != nil {
return nil, fmt.Errorf("reading schema file %q: %v", schemaFile, err)
}
}
if data == nil {
resp, err := http.Get(schemaURL)
if err != nil {
return nil, fmt.Errorf("downloading schema: %v", err)
}
defer resp.Body.Close()
if resp.StatusCode != http.StatusOK {
return nil, fmt.Errorf("downloading schema: %v", resp.Status)
}
data, err = io.ReadAll(resp.Body)
if err != nil {
return nil, fmt.Errorf("reading schema body: %v", err)
}
if schemaFile != "" {
if err := os.WriteFile(schemaFile, data, 0666); err != nil {
return nil, fmt.Errorf("persisting schema: %v", err)
}
}
}
return data, nil
}
// Suffixes of type names with a meta field.
var metaSuffixes = []string{"Params", "ParamsFor", "Result", "ResultFor"}
func writeDecl(configName string, config typeConfig, def *jsonschema.Schema, named map[string]*bytes.Buffer) error {
var w io.Writer = io.Discard
var typeName string
if typeName = config.Name; typeName != "-" {
if typeName == "" {
typeName = configName
}
if _, ok := named[typeName]; ok {
return nil
}
// The JSON schema does not accurately represent the source of truth, which is typescript.
// Every Params and Result type should have a _meta property.
// Also, those with a progress token will turn into a struct; we want the progress token to
// be a map item. So replace all metas.
for _, s := range metaSuffixes {
if strings.HasSuffix(typeName, s) {
def.Properties["_meta"] = metaSchema
break
}
}
buf := new(bytes.Buffer)
w = buf
named[typeName] = buf
if def.Description != "" {
fmt.Fprintf(buf, "%s\n", toComment(def.Description))
}
typeParams := new(strings.Builder)
if len(config.TypeParams) > 0 {
typeParams.WriteByte('[')
for i, p := range config.TypeParams {
if i > 0 {
typeParams.WriteString(", ")
}
fmt.Fprintf(typeParams, "%s %s", p[0], p[1])
}
typeParams.WriteByte(']')
}
fmt.Fprintf(buf, "type %s%s ", typeName, typeParams)
}
if err := writeType(w, &config, def, named); err != nil {
return err // Better error here?
}
fmt.Fprintf(w, "\n")
// Any decl with a _meta field gets a GetMeta method.
if _, ok := def.Properties["_meta"]; ok {
targs := new(strings.Builder)
if len(config.TypeParams) > 0 {
targs.WriteByte('[')
for i, p := range config.TypeParams {
if i > 0 {
targs.WriteString(", ")
}
fmt.Fprintf(targs, "%s", p[0])
}
targs.WriteByte(']')
}
fmt.Fprintf(w, "\nfunc (x *%s%s) GetMeta() *Meta { return &x.Meta }", typeName, targs)
}
if _, ok := def.Properties["cursor"]; ok {
fmt.Fprintf(w, "\nfunc (x *%s) cursorPtr() *string { return &x.Cursor }", typeName)
}
if _, ok := def.Properties["nextCursor"]; ok {
fmt.Fprintf(w, "\nfunc (x *%s) nextCursorPtr() *string { return &x.NextCursor }", typeName)
}
// Some types have generic counterparts.
var typeArg, substField string
switch typeName {
case "CallToolParams":
typeName = "CallToolParamsFor"
typeArg = "In"
substField = "Arguments"
case "CallToolResult":
typeName = "CallToolResultFor"
typeArg = "Out"
substField = "StructuredContent"
}
if typeArg != "" {
fmt.Fprintf(w, "\n\ntype %s[%s any]", typeName, typeArg)
if config.Fields != nil {
config.Fields[substField].Substitute = typeArg
}
if err := writeType(w, &config, def, named); err != nil {
return err
}
fmt.Fprintf(w, "\nfunc (x *%s[%s]) GetMeta() *Meta {return &x.Meta}", typeName, typeArg)
}
return nil
}
// writeType writes the type definition to the given writer.
//
// If path is non-empty, it is the path to the field using this type, for the
// purpose of detecting field rewrites (see [fieldRewrite]).
//
// named is the in-progress collection of type definitions. New named types may
// be added during writeType, if they are extracted from inner fields.
func writeType(w io.Writer, config *typeConfig, def *jsonschema.Schema, named map[string]*bytes.Buffer) error {
// Use type names for Named types.
name, resolved := deref(def)
if name != "" {
// TODO: this check is not quite right: we should really panic if the
// definition is missing, *but only if w is not io.Discard*. That's not a
// great API: see if we can do something more explicit than io.Discard.
if cfg, ok := declarations[name]; ok {
if cfg.Name == "-" && cfg.Substitute == "" {
panic(fmt.Sprintf("referenced type %q cannot be referred to (no name or substitution)", name))
}
if cfg.Substitute != "" {
name = cfg.Substitute
} else if cfg.Name != "" {
name = cfg.Name
}
if isStruct(resolved) {
w.Write([]byte{'*'})
}
}
w.Write([]byte(name))
return nil
}
// For types that explicitly allow additional properties, we can either
// unmarshal them into a map[string]any, or delay unmarshalling with
// json.RawMessage. We use any.
if def.Type == "object" && canHaveAdditionalProperties(def) && def.Properties == nil {
w.Write([]byte("map[string]"))
return writeType(w, nil, def.AdditionalProperties, named)
}
if def.Type == "" {
// special case: recognize Content
if slices.ContainsFunc(def.AnyOf, func(s *jsonschema.Schema) bool {
return s.Ref == "#/definitions/TextContent"
}) {
fmt.Fprintf(w, "*Content")
} else {
// E.g. union types.
fmt.Fprintf(w, "any")
}
} else {
switch def.Type {
case "array":
fmt.Fprintf(w, "[]")
return writeType(w, nil, def.Items, named)
case "boolean":
fmt.Fprintf(w, "bool")
case "integer":
fmt.Fprintf(w, "int64")
// not handled: "null"
case "number":
// We could use json.Number here; use float64 for simplicity.
fmt.Fprintf(w, "float64")
case "object":
fmt.Fprintf(w, "struct {\n")
for name, fieldDef := range util.Sorted(def.Properties) {
if fieldDef.Description != "" {
fmt.Fprintf(w, "%s\n", toComment(fieldDef.Description))
}
if name == "_meta" {
fmt.Fprintln(w, "\tMeta Meta `json:\"_meta,omitempty\"`")
continue
}
export := exportName(name)
fmt.Fprintf(w, "\t%s ", export)
required := slices.Contains(def.Required, name)
// If the field is a struct type, indirect with a
// pointer so that it can be empty as defined by encoding/json.
// This also future-proofs against the struct getting large.
fieldTypeSchema := fieldDef
// If the schema is a reference, dereference it.
if _, rs := deref(fieldDef); rs != nil {
fieldTypeSchema = rs
}
needPointer := isStruct(fieldTypeSchema)
// Special case: there are no sampling or logging capabilities defined,
// but we want them to be structs for future expansion.
if !needPointer && (name == "sampling" || name == "logging") {
needPointer = true
}
if config != nil && config.Fields[export] != nil {
r := config.Fields[export]
if r.Substitute != "" {
fmt.Fprintf(w, r.Substitute)
} else {
assert(r.Name != "-", "missing ExtractTo")
typename := export
if r.Name != "" {
typename = r.Name
}
if err := writeDecl(typename, *r, fieldDef, named); err != nil {
return err
}
if needPointer {
fmt.Fprintf(w, "*")
}
fmt.Fprintf(w, typename)
}
} else if err := writeType(w, nil, fieldDef, named); err != nil {
return fmt.Errorf("failed to write type for field %s: %v", export, err)
}
fmt.Fprintf(w, " `json:\"%s", name)
if !required {
fmt.Fprint(w, ",omitempty")
}
fmt.Fprint(w, "\"`\n")
}
fmt.Fprintf(w, "}")
case "string":
fmt.Fprintf(w, "string")
default:
fmt.Fprintf(w, "any")
}
}
return nil
}
// toComment converts a JSON schema description to a Go comment.
func toComment(description string) string {
var (
buf strings.Builder
lineBuf strings.Builder
)
const wrapAt = 80
for line := range strings.SplitSeq(description, "\n") {
// Start a new paragraph, if the current is nonempty.
if len(line) == 0 && lineBuf.Len() > 0 {
buf.WriteString(lineBuf.String())
lineBuf.Reset()
buf.WriteString("\n//\n")
continue
}
// Otherwise, fill in the current paragraph.
for field := range strings.FieldsSeq(line) {
if lineBuf.Len() > 0 && lineBuf.Len()+len(" ")+len(field) > wrapAt {
buf.WriteString(lineBuf.String())
buf.WriteRune('\n')
lineBuf.Reset()
}
if lineBuf.Len() == 0 {
lineBuf.WriteString("//")
}
lineBuf.WriteString(" ")
lineBuf.WriteString(field)
}
}
if lineBuf.Len() > 0 {
buf.WriteString(lineBuf.String())
}
return strings.TrimRight(buf.String(), "\n")
}
// The MCP spec improperly uses the absence of the additionalProperties keyword to
// mean that additional properties are not allowed. In fact, it means just the opposite
// (https://json-schema.org/draft-07/draft-handrews-json-schema-validation-01#rfc.section.6.5.6).
// If the MCP spec wants to allow additional properties, it will write "true" or
// an object explicitly.
func canHaveAdditionalProperties(s *jsonschema.Schema) bool {
ap := s.AdditionalProperties
return ap != nil && !reflect.DeepEqual(ap, &jsonschema.Schema{Not: &jsonschema.Schema{}})
}
// exportName returns an exported name for a Go symbol, based on the given name
// in the JSON schema, removing leading underscores and capitalizing.
// It also rewrites initialisms.
func exportName(s string) string {
if strings.HasPrefix(s, "_") {
s = s[1:]
}
s = strings.ToUpper(s[:1]) + s[1:]
// Replace an initialism if it is its own "word": see the init function below for
// a definition.
// There is probably a clever way to write this whole thing with one regexp and
// a Replace method, but it would be quite obscure.
// This doesn't have to be fast, because the first match will rarely succeed.
for ism, re := range initialisms {
replacement := strings.ToUpper(ism)
// Find the index of one match at a time, and replace. (We can't find all
// at once, because the replacement will change the indices.)
for {
if loc := re.FindStringIndex(s); loc != nil {
// Don't replace the rune after the initialism, if any.
end := loc[1]
if end < len(s) {
end--
}
s = s[:loc[0]] + replacement + s[end:]
} else {
break
}
}
}
return s
}
// deref dereferences s.Ref.
// If s.Ref refers to a schema in the Definitions section, deref
// returns the definition name and the associated schema.
// Otherwise, deref returns "", nil.
func deref(s *jsonschema.Schema) (name string, _ *jsonschema.Schema) {
name, ok := strings.CutPrefix(s.Ref, "#/definitions/")
if !ok {
return "", nil
}
return name, s.ResolvedRef()
}
// isStruct reports whether s should be translated to a struct.
func isStruct(s *jsonschema.Schema) bool {
return s.Type == "object" && s.Properties != nil && !canHaveAdditionalProperties(s)
}
// The schema for "_meta".
// We only need the description: the rest is a special case.
var metaSchema = &jsonschema.Schema{
Description: "This property is reserved by the protocol to allow clients and servers to attach additional metadata to their responses.",
}
// schemaJSON returns the JSON for s.
// For debugging.
func schemaJSON(s *jsonschema.Schema) string {
data, err := json.Marshal(s)
if err != nil {
return fmt.Sprintf("<jsonschema.Schema:%v>", err)
}
return string(data)
}
// Map from initialism to the regexp that matches it.
var initialisms = map[string]*regexp.Regexp{
"Id": nil,
"Url": nil,
"Uri": nil,
"Mime": nil,
}
func init() {
for ism := range initialisms {
// Match ism if it is at the end, or followed by an uppercase letter or a number.
initialisms[ism] = regexp.MustCompile(ism + `($|[A-Z0-9])`)
}
}
func assert(cond bool, msg string) {
if !cond {
panic(msg)
}
}

1
mcp/mcp.go
View file

@ -2,7 +2,6 @@
// Use of this source code is governed by an MIT-style // Use of this source code is governed by an MIT-style
// license that can be found in the LICENSE file. // license that can be found in the LICENSE file.
//go:generate go run generate.go
//go:generate ../internal/readme/build.sh //go:generate ../internal/readme/build.sh
// The mcp package provides an SDK for writing model context protocol clients // The mcp package provides an SDK for writing model context protocol clients

20
mcp/protocol.go
View file

@ -2,8 +2,6 @@
// Use of this source code is governed by an MIT-style // Use of this source code is governed by an MIT-style
// license that can be found in the LICENSE file. // license that can be found in the LICENSE file.
// Code generated by generate.go. DO NOT EDIT.
package mcp package mcp
import ( import (
@ -103,8 +101,7 @@ func (x *CancelledParams) GetMeta() *Meta { return &x.Meta }
// additional capabilities. // additional capabilities.
type ClientCapabilities struct { type ClientCapabilities struct {
// Experimental, non-standard capabilities that the client supports. // Experimental, non-standard capabilities that the client supports.
Experimental map[string]struct { Experimental map[string]struct{} `json:"experimental,omitempty"`
} `json:"experimental,omitempty"`
// Present if the client supports listing roots. // Present if the client supports listing roots.
Roots struct { Roots struct {
// Whether the client supports notifications for changes to the roots list. // Whether the client supports notifications for changes to the roots list.
@ -127,8 +124,7 @@ type CreateMessageParams struct {
Messages []*SamplingMessage `json:"messages"` Messages []*SamplingMessage `json:"messages"`
// Optional metadata to pass through to the LLM provider. The format of this // Optional metadata to pass through to the LLM provider. The format of this
// metadata is provider-specific. // metadata is provider-specific.
Metadata struct { Metadata struct{} `json:"metadata,omitempty"`
} `json:"metadata,omitempty"`
// The server's preferences for which model to select. The client MAY ignore // The server's preferences for which model to select. The client MAY ignore
// these preferences. // these preferences.
ModelPreferences *ModelPreferences `json:"modelPreferences,omitempty"` ModelPreferences *ModelPreferences `json:"modelPreferences,omitempty"`
@ -585,8 +581,7 @@ type RootsListChangedParams struct {
func (x *RootsListChangedParams) GetMeta() *Meta { return &x.Meta } func (x *RootsListChangedParams) GetMeta() *Meta { return &x.Meta }
// Present if the client supports sampling from an LLM. // Present if the client supports sampling from an LLM.
type SamplingCapabilities struct { type SamplingCapabilities struct{}
}
// Describes a message issued to or received from an LLM API. // Describes a message issued to or received from an LLM API.
type SamplingMessage struct { type SamplingMessage struct {
@ -673,8 +668,7 @@ type implementation struct {
} }
// Present if the server supports sending log messages to the client. // Present if the server supports sending log messages to the client.
type loggingCapabilities struct { type loggingCapabilities struct{}
}
// Present if the server offers any prompt templates. // Present if the server offers any prompt templates.
type promptCapabilities struct { type promptCapabilities struct {
@ -695,11 +689,9 @@ type resourceCapabilities struct {
// additional capabilities. // additional capabilities.
type serverCapabilities struct { type serverCapabilities struct {
// Present if the server supports argument autocompletion suggestions. // Present if the server supports argument autocompletion suggestions.
Completions struct { Completions struct{} `json:"completions,omitempty"`
} `json:"completions,omitempty"`
// Experimental, non-standard capabilities that the server supports. // Experimental, non-standard capabilities that the server supports.
Experimental map[string]struct { Experimental map[string]struct{} `json:"experimental,omitempty"`
} `json:"experimental,omitempty"`
// Present if the server supports sending log messages to the client. // Present if the server supports sending log messages to the client.
Logging *loggingCapabilities `json:"logging,omitempty"` Logging *loggingCapabilities `json:"logging,omitempty"`
// Present if the server offers any prompt templates. // Present if the server offers any prompt templates.