docs: add feature and troubleshooting documentation (#463)
Add a framework for feature documentation, and start populating it with our SDK documentation. This framework is as follows: - internal/docs/**.src.md is the markdown source for the docs/ directory. - The x/example/internal/cmd/weave tool is used to compile these docs to the top-level docs, supporting both linked code samples and generated tables of contents. - The readme-check workflow is updated to check these docs as well. - The structure of these docs follows the MCP spec. - Wherever possible, example code is linked from actual Go documentation examples, so that it is testable. Some minor modifications to the weave tool were made to support this framework. Additionally, partially fill out this documentation with content on base protocol and client features, as well as troubleshooting help. Along the way, a bug was encountered that our LoggingTransport was not concurrency safe. This is fixed with a mutex. Fixes https://github.com/modelcontextprotocol/go-sdk/issues/466 Fixes https://github.com/modelcontextprotocol/go-sdk/issues/409 Updates https://github.com/modelcontextprotocol/go-sdk/issues/442
This commit is contained in:
Robert Findley
GitHub
parent
ab4d6218c6
commit
ac2f175214
5 changed files with 1566 additions and 30 deletions
40
docs/README.md
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40
docs/README.md
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@ -0,0 +1,40 @@
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<!-- Autogenerated by weave; DO NOT EDIT -->
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These docs are a work-in-progress.
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# Features
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These docs mirror the [official MCP spec](https://modelcontextprotocol.io/specification/2025-06-18).
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## Base Protocol
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1. [Lifecycle (Clients, Servers, and Sessions)](protocol.md#lifecycle).
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1. [Transports](protocol.md#transports)
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1. [Stdio transport](protocol.md#stdio-transport)
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1. [Streamable transport](protocol.md#streamable-transport)
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1. [Custom transports](protocol.md#stateless-mode)
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1. [Authorization](protocol.md#authorization)
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1. [Security](protocol.md#security)
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1. [Utilities](protocol.md#utilities)
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1. [Cancellation](utilities.md#cancellation)
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1. [Ping](utilities.md#ping)
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1. [Progress](utilities.md#progress)
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## Client Features
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1. [Roots](client.md#roots)
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1. [Sampling](client.md#sampling)
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1. [Elicitation](clients.md#elicitation)
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## Server Features
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1. [Prompts](server.md#prompts)
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1. [Resources](server.md#resources)
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1. [Tools](tools.md)
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1. [Utilities](server.md#utilities)
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1. [Completion](server.md#completion)
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1. [Logging](server.md#logging)
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1. [Pagination](server.md#pagination)
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# TroubleShooting
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See [troubleshooting.md](troubleshooting.md) for a troubleshooting guide.
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168
docs/client.md
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168
docs/client.md
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<!-- Autogenerated by weave; DO NOT EDIT -->
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# Support for MCP client features
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1. [Roots](#roots)
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1. [Sampling](#sampling)
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1. [Elicitation](#elicitation)
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## Roots
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MCP allows clients to specify a set of filesystem
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["roots"](https://modelcontextprotocol.io/specification/2025-06-18/client/roots).
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The SDK supports this as follows:
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**Client-side**: The SDK client always has the `roots.listChanged` capability.
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To add roots to a client, use the
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[`Client.AddRoots`](https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/mcp#AddRoots)
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and
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[`Client.RemoveRoots`](https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/mcp#Client.RemoveRoots)
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methods. If any servers are already [connected](protocol.md#lifecycle) to the
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client, a call to `AddRoot` or `RemoveRoots` will result in a
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`notifications/roots/list_changed` notification to each connected server.
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**Server-side**: To query roots from the server, use the
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[`ServerSession.ListRoots`](https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/mcp#ServerSession.ListRoots)
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method. To receive notifications about root changes, set
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[`ServerOptions.RootsListChangedHandler`](https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/mcp#ServerOptions.RootsListChangedHandler).
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```go
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func Example_roots() {
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ctx := context.Background()
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// Create a client with a single root.
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c := mcp.NewClient(&mcp.Implementation{Name: "client", Version: "v0.0.1"}, nil)
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c.AddRoots(&mcp.Root{URI: "file://a"})
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// Now create a server with a handler to receive notifications about roots.
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rootsChanged := make(chan struct{})
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handleRootsChanged := func(ctx context.Context, req *mcp.RootsListChangedRequest) {
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rootList, err := req.Session.ListRoots(ctx, nil)
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if err != nil {
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log.Fatal(err)
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}
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var roots []string
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for _, root := range rootList.Roots {
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roots = append(roots, root.URI)
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}
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fmt.Println(roots)
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close(rootsChanged)
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}
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s := mcp.NewServer(&mcp.Implementation{Name: "server", Version: "v0.0.1"}, &mcp.ServerOptions{
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RootsListChangedHandler: handleRootsChanged,
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})
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// Connect the server and client...
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t1, t2 := mcp.NewInMemoryTransports()
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if _, err := s.Connect(ctx, t1, nil); err != nil {
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log.Fatal(err)
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}
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if _, err := c.Connect(ctx, t2, nil); err != nil {
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log.Fatal(err)
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}
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// ...and add a root. The server is notified about the change.
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c.AddRoots(&mcp.Root{URI: "file://b"})
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<-rootsChanged
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// Output: [file://a file://b]
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}
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```
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## Sampling
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[Sampling](https://modelcontextprotocol.io/specification/2025-06-18/client/sampling)
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is a way for servers to leverage the client's AI capabilities. It is
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implemented in the SDK as follows:
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**Client-side**: To add the `sampling` capability to a client, set
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[`ClientOptions.CreateMessageHandler`](https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/mcp#ClientOptions.CreateMessageHandler).
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This function is invoked whenever the server requests sampling.
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**Server-side**: To use sampling from the server, call
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[`ServerSession.CreateMessage`](https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/mcp#ServerSession.CreateMessage).
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```go
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func Example_sampling() {
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ctx := context.Background()
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// Create a client with a sampling handler.
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c := mcp.NewClient(&mcp.Implementation{Name: "client", Version: "v0.0.1"}, &mcp.ClientOptions{
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CreateMessageHandler: func(_ context.Context, req *mcp.CreateMessageRequest) (*mcp.CreateMessageResult, error) {
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return &mcp.CreateMessageResult{
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Content: &mcp.TextContent{
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Text: "would have created a message",
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},
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}, nil
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},
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})
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// Connect the server and client...
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ct, st := mcp.NewInMemoryTransports()
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s := mcp.NewServer(&mcp.Implementation{Name: "server", Version: "v0.0.1"}, nil)
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session, err := s.Connect(ctx, st, nil)
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if err != nil {
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log.Fatal(err)
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}
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defer session.Close()
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if _, err := c.Connect(ctx, ct, nil); err != nil {
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log.Fatal(err)
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}
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msg, err := session.CreateMessage(ctx, &mcp.CreateMessageParams{})
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if err != nil {
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log.Fatal(err)
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}
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fmt.Println(msg.Content.(*mcp.TextContent).Text)
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// Output: would have created a message
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}
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```
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## Elicitation
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[Elicitation](https://modelcontextprotocol.io/specification/2025-06-18/client/elicitation)
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allows servers to request user inputs. It is implemented in the SDK as follows:
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**Client-side**: To add the `elicitation` capability to a client, set
|
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[`ClientOptions.ElicitationHandler`](https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/mcp#ClientOptions.ElicitationHandler).
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The elicitation handler must return a result that matches the requested schema;
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otherwise, elicitation returns an error.
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**Server-side**: To use elicitation from the server, call
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[`ServerSession.Elicit`](https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/mcp#ServerSession.Elicit).
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```go
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func Example_elicitation() {
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ctx := context.Background()
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ct, st := mcp.NewInMemoryTransports()
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s := mcp.NewServer(&mcp.Implementation{Name: "server", Version: "v0.0.1"}, nil)
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ss, err := s.Connect(ctx, st, nil)
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if err != nil {
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log.Fatal(err)
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}
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defer ss.Close()
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c := mcp.NewClient(testImpl, &mcp.ClientOptions{
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ElicitationHandler: func(context.Context, *mcp.ElicitRequest) (*mcp.ElicitResult, error) {
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return &mcp.ElicitResult{Action: "accept", Content: map[string]any{"test": "value"}}, nil
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},
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})
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if _, err := c.Connect(ctx, ct, nil); err != nil {
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log.Fatal(err)
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}
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res, err := ss.Elicit(ctx, &mcp.ElicitParams{
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Message: "This should fail",
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RequestedSchema: &jsonschema.Schema{
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Type: "object",
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Properties: map[string]*jsonschema.Schema{
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"test": {Type: "string"},
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},
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},
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})
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if err != nil {
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log.Fatal(err)
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}
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fmt.Println(res.Content["test"])
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// Output: value
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}
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```
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368
docs/protocol.md
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368
docs/protocol.md
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<!-- Autogenerated by weave; DO NOT EDIT -->
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# Support for the MCP base protocol
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1. [Lifecycle](#lifecycle)
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1. [Transports](#transports)
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1. [Stdio Transport](#stdio-transport)
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1. [Streamable Transport](#streamable-transport)
|
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1. [Custom transports](#custom-transports)
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1. [Concurrency](#concurrency)
|
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1. [Authorization](#authorization)
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1. [Security](#security)
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1. [Utilities](#utilities)
|
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1. [Cancellation](#cancellation)
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1. [Ping](#ping)
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1. [Progress](#progress)
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## Lifecycle
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||||
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The SDK provides an API for defining both MCP clients and servers, and
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connecting them over various transports. When a client and server are
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connected, it creates a logical session, which follows the MCP spec's
|
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[lifecycle](https://modelcontextprotocol.io/specification/2025-06-18/basic/lifecycle).
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|
||||
In this SDK, both a
|
||||
[`Client`](https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/mcp#Client)
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and
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||||
[`Server`](https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/mcp#Server)
|
||||
can handle multiple peers. Every time a new peer is connected, it creates a new
|
||||
session.
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||||
|
||||
- A `Client` is a logical MCP client, configured with various
|
||||
[`ClientOptions`](https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/mcp#ClientOptions).
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- When a client is connected to a server using
|
||||
[`Client.Connect`](https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/mcp#Client.Connect),
|
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it creates a
|
||||
[`ClientSession`](https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/mcp#ClientSession).
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This session is initialized during the `Connect` method, and provides methods
|
||||
to communicate with the server peer.
|
||||
- A `Server` is a logical MCP server, configured with various
|
||||
[`ServerOptions`](https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/mcp#ServerOptions).
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- When a server is connected to a client using
|
||||
[`Server.Connect`](https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/mcp#Server.Connect),
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||||
it creates a
|
||||
[`ServerSession`](https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/mcp#ServerSession).
|
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This session is not initialized until the client sends the
|
||||
`notifications/initialized` message. Use `ServerOptions.InitializedHandler`
|
||||
to listen for this event, or just use the session through various feature
|
||||
handlers (such as a `ToolHandler`). Requests to the server are rejected until
|
||||
the client has initialized the session.
|
||||
|
||||
Both `ClientSession` and `ServerSession` have a `Close` method to terminate the
|
||||
session, and a `Wait` method to await session termination by the peer. Typically,
|
||||
it is the client's responsibility to end the session.
|
||||
|
||||
```go
|
||||
func Example_lifecycle() {
|
||||
ctx := context.Background()
|
||||
|
||||
// Create a client and server.
|
||||
// Wait for the client to initialize the session.
|
||||
client := mcp.NewClient(&mcp.Implementation{Name: "client", Version: "v0.0.1"}, nil)
|
||||
server := mcp.NewServer(&mcp.Implementation{Name: "server", Version: "v0.0.1"}, &mcp.ServerOptions{
|
||||
InitializedHandler: func(context.Context, *mcp.InitializedRequest) {
|
||||
fmt.Println("initialized!")
|
||||
},
|
||||
})
|
||||
|
||||
// Connect the server and client using in-memory transports.
|
||||
//
|
||||
// Connect the server first so that it's ready to receive initialization
|
||||
// messages from the client.
|
||||
t1, t2 := mcp.NewInMemoryTransports()
|
||||
serverSession, err := server.Connect(ctx, t1, nil)
|
||||
if err != nil {
|
||||
log.Fatal(err)
|
||||
}
|
||||
clientSession, err := client.Connect(ctx, t2, nil)
|
||||
if err != nil {
|
||||
log.Fatal(err)
|
||||
}
|
||||
|
||||
// Now shut down the session by closing the client, and waiting for the
|
||||
// server session to end.
|
||||
if err := clientSession.Close(); err != nil {
|
||||
log.Fatal(err)
|
||||
}
|
||||
if err := serverSession.Wait(); err != nil {
|
||||
log.Fatal(err)
|
||||
}
|
||||
// Output: initialized!
|
||||
}
|
||||
```
|
||||
|
||||
## Transports
|
||||
|
||||
A
|
||||
[transport](https://modelcontextprotocol.io/specification/2025-06-18/basic/transports)
|
||||
can be used to send JSON-RPC messages from client to server, or vice-versa.
|
||||
|
||||
In the SDK, this is achieved by implementing the
|
||||
[`Transport`](https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/mcp#Transport)
|
||||
interface, which creates a (logical) bidirectional stream of JSON-RPC messages.
|
||||
Most transport implementations described below are specific to either the
|
||||
client or server: a "client transport" is something that can be used to connect
|
||||
a client to a server, and a "server transport" is something that can be used to
|
||||
connect a server to a client. However, it's possible for a transport to be both
|
||||
a client and server transport, such as the `InMemoryTransport` used in the
|
||||
lifecycle example above.
|
||||
|
||||
Transports should not be reused for multiple connections: if you need to create
|
||||
multiple connections, use different transports.
|
||||
|
||||
### Stdio Transport
|
||||
|
||||
In the
|
||||
[`stdio`](https://modelcontextprotocol.io/specification/2025-06-18/basic/transports#stdio)
|
||||
transport clients communicate with an MCP server running in a subprocess using
|
||||
newline-delimited JSON over its stdin/stdout.
|
||||
|
||||
**Client-side**: the client side of the `stdio` transport is implemented by
|
||||
[`CommandTransport`](https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/mcp#CommandTransport),
|
||||
which starts the a `exec.Cmd` as a subprocess and communicates over its
|
||||
stdin/stdout.
|
||||
|
||||
**Server-side**: the server side of the `stdio` transport is implemented by
|
||||
`StdioTransport`, which connects over the current processes `os.Stdin` and
|
||||
`os.Stdout`.
|
||||
|
||||
### Streamable Transport
|
||||
|
||||
The [streamable
|
||||
transport](https://modelcontextprotocol.io/specification/2025-06-18/basic/transports#streamable-http)
|
||||
API is implemented across three types:
|
||||
|
||||
- `StreamableHTTPHandler`: an`http.Handler` that serves streamable MCP
|
||||
sessions.
|
||||
- `StreamableServerTransport`: a `Transport` that implements the server side of
|
||||
the streamable transport.
|
||||
- `StreamableClientTransport`: a `Transport` that implements the client side of
|
||||
the streamable transport.
|
||||
|
||||
To create a streamable MCP server, you create a `StreamableHTTPHandler` and
|
||||
pass it an `mcp.Server`:
|
||||
|
||||
```go
|
||||
func ExampleStreamableHTTPHandler() {
|
||||
// Create a new streamable handler, using the same MCP server for every request.
|
||||
//
|
||||
// Here, we configure it to serves application/json responses rather than
|
||||
// text/event-stream, just so the output below doesn't use random event ids.
|
||||
server := mcp.NewServer(&mcp.Implementation{Name: "server", Version: "v0.1.0"}, nil)
|
||||
handler := mcp.NewStreamableHTTPHandler(func(r *http.Request) *mcp.Server {
|
||||
return server
|
||||
}, &mcp.StreamableHTTPOptions{JSONResponse: true})
|
||||
httpServer := httptest.NewServer(handler)
|
||||
defer httpServer.Close()
|
||||
|
||||
// The SDK is currently permissive of some missing keys in "params".
|
||||
resp := mustPostMessage(`{"jsonrpc": "2.0", "id": 1, "method":"initialize", "params": {}}`, httpServer.URL)
|
||||
fmt.Println(resp)
|
||||
// Output:
|
||||
// {"jsonrpc":"2.0","id":1,"result":{"capabilities":{"logging":{}},"protocolVersion":"2025-06-18","serverInfo":{"name":"server","version":"v0.1.0"}}}
|
||||
}
|
||||
```
|
||||
|
||||
The `StreamableHTTPHandler` handles the HTTP requests and creates a new
|
||||
`StreamableServerTransport` for each new session. The transport is then used to
|
||||
communicate with the client.
|
||||
|
||||
On the client side, you create a `StreamableClientTransport` and use it to
|
||||
connect to the server:
|
||||
|
||||
```go
|
||||
transport := &mcp.StreamableClientTransport{
|
||||
Endpoint: "http://localhost:8080/mcp",
|
||||
}
|
||||
client, err := mcp.Connect(ctx, transport, &mcp.ClientOptions{...})
|
||||
```
|
||||
|
||||
The `StreamableClientTransport` handles the HTTP requests and communicates with
|
||||
the server using the streamable transport protocol.
|
||||
|
||||
#### Stateless Mode
|
||||
|
||||
<!-- TODO -->
|
||||
|
||||
#### Sessionless mode
|
||||
|
||||
<!-- TODO -->
|
||||
|
||||
### Custom transports
|
||||
|
||||
<!-- TODO -->
|
||||
|
||||
### Concurrency
|
||||
|
||||
In general, MCP offers no guarantees about concurrency semantics: if a client
|
||||
or server sends a notification, the spec says nothing about when the peer
|
||||
observes that notification relative to other request. However, the Go SDK
|
||||
implements the following heuristics:
|
||||
|
||||
- If a notifying method (such as `notifications/progress` or
|
||||
`notifications/initialized`) returns, then it is guaranteed that the peer
|
||||
observes that notification before other notifications or calls from the same
|
||||
client goroutine.
|
||||
- Calls (such as `tools/call`) are handled asynchronously with respect to
|
||||
each other.
|
||||
|
||||
See
|
||||
[modelcontextprotocol/go-sdk#26](https://github.com/modelcontextprotocol/go-sdk/issues/26)
|
||||
for more background.
|
||||
|
||||
## Authorization
|
||||
|
||||
<!-- TODO -->
|
||||
|
||||
## Security
|
||||
|
||||
<!-- TODO -->
|
||||
|
||||
## Utilities
|
||||
|
||||
### Cancellation
|
||||
|
||||
Cancellation is implemented with context cancellation. Cancelling a context
|
||||
used in a method on `ClientSession` or `ServerSession` will terminate the RPC
|
||||
and send a "notifications/cancelled" message to the peer.
|
||||
|
||||
When an RPC exits due to a cancellation error, there's a guarantee that the
|
||||
cancellation notification has been sent, but there's no guarantee that the
|
||||
server has observed it (see [concurrency](#concurrency)).
|
||||
|
||||
```go
|
||||
func Example_cancellation() {
|
||||
// For this example, we're going to be collecting observations from the
|
||||
// server and client.
|
||||
var clientResult, serverResult string
|
||||
var wg sync.WaitGroup
|
||||
wg.Add(2)
|
||||
|
||||
// Create a server with a single slow tool.
|
||||
// When the client cancels its request, the server should observe
|
||||
// cancellation.
|
||||
server := mcp.NewServer(&mcp.Implementation{Name: "server", Version: "v0.0.1"}, nil)
|
||||
started := make(chan struct{}, 1) // signals that the server started handling the tool call
|
||||
mcp.AddTool(server, &mcp.Tool{Name: "slow"}, func(ctx context.Context, req *mcp.CallToolRequest, _ any) (*mcp.CallToolResult, any, error) {
|
||||
started <- struct{}{}
|
||||
defer wg.Done()
|
||||
select {
|
||||
case <-time.After(5 * time.Second):
|
||||
serverResult = "tool done"
|
||||
case <-ctx.Done():
|
||||
serverResult = "tool canceled"
|
||||
}
|
||||
return &mcp.CallToolResult{}, nil, nil
|
||||
})
|
||||
|
||||
// Connect a client to the server.
|
||||
client := mcp.NewClient(&mcp.Implementation{Name: "client", Version: "v0.0.1"}, nil)
|
||||
ctx := context.Background()
|
||||
t1, t2 := mcp.NewInMemoryTransports()
|
||||
if _, err := server.Connect(ctx, t1, nil); err != nil {
|
||||
log.Fatal(err)
|
||||
}
|
||||
session, err := client.Connect(ctx, t2, nil)
|
||||
if err != nil {
|
||||
log.Fatal(err)
|
||||
}
|
||||
defer session.Close()
|
||||
|
||||
// Make a tool call, asynchronously.
|
||||
ctx, cancel := context.WithCancel(context.Background())
|
||||
go func() {
|
||||
defer wg.Done()
|
||||
_, err = session.CallTool(ctx, &mcp.CallToolParams{Name: "slow"})
|
||||
clientResult = fmt.Sprintf("%v", err)
|
||||
}()
|
||||
|
||||
// As soon as the server has started handling the call, cancel it from the
|
||||
// client side.
|
||||
<-started
|
||||
cancel()
|
||||
wg.Wait()
|
||||
|
||||
fmt.Println(clientResult)
|
||||
fmt.Println(serverResult)
|
||||
// Output:
|
||||
// context canceled
|
||||
// tool canceled
|
||||
}
|
||||
```
|
||||
|
||||
### Ping
|
||||
|
||||
[Ping](https://modelcontextprotocol.io/specification/2025-06-18/basic/utilities/ping)
|
||||
support is symmetrical for client and server.
|
||||
|
||||
To initiate a ping, call
|
||||
[`ClientSession.Ping`](https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/mcp#ClientSession.Ping)
|
||||
or
|
||||
[`ServerSession.Ping`](https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/mcp#ServerSession.Ping).
|
||||
|
||||
To have the client or server session automatically ping its peer, and close the
|
||||
session if the ping fails, set
|
||||
[`ClientOptions.KeepAlive`](https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/mcp#ClientOptions.KeepAlive)
|
||||
or
|
||||
[`ServerOptions.KeepAlive`](https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/mcp#ServerOptions.KeepAlive).
|
||||
|
||||
### Progress
|
||||
|
||||
[Progress](https://modelcontextprotocol.io/specification/2025-06-18/basic/utilities/progress)
|
||||
reporting is possible by reading the progress token from request metadata and
|
||||
calling either
|
||||
[`ClientSession.NotifyProgress`](https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/mcp#ClientSession.NotifyProgress)
|
||||
or
|
||||
[`ServerSession.NotifyProgress`](https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/mcp#ServerSession.NotifyProgress).
|
||||
To listen to progress notifications, set
|
||||
[`ClientOptions.ProgressNotificationHandler`](https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/mcp#ClientOptions.ProgressNotificationHandler)
|
||||
or
|
||||
[`ServerOptions.ProgressNotificationHandler`](https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/mcp#ServerOptions.ProgressNotificationHandler).
|
||||
|
||||
Issue #460 discusses some potential ergonomic improvements to this API.
|
||||
|
||||
```go
|
||||
func Example_progress() {
|
||||
server := mcp.NewServer(&mcp.Implementation{Name: "server", Version: "v0.0.1"}, nil)
|
||||
mcp.AddTool(server, &mcp.Tool{Name: "makeProgress"}, func(ctx context.Context, req *mcp.CallToolRequest, _ any) (*mcp.CallToolResult, any, error) {
|
||||
if token := req.Params.GetProgressToken(); token != nil {
|
||||
for i := range 3 {
|
||||
params := &mcp.ProgressNotificationParams{
|
||||
Message: "frobbing widgets",
|
||||
ProgressToken: token,
|
||||
Progress: float64(i),
|
||||
Total: 2,
|
||||
}
|
||||
req.Session.NotifyProgress(ctx, params) // ignore error
|
||||
}
|
||||
}
|
||||
return &mcp.CallToolResult{}, nil, nil
|
||||
})
|
||||
client := mcp.NewClient(&mcp.Implementation{Name: "client", Version: "v0.0.1"}, &mcp.ClientOptions{
|
||||
ProgressNotificationHandler: func(_ context.Context, req *mcp.ProgressNotificationClientRequest) {
|
||||
fmt.Printf("%s %.0f/%.0f\n", req.Params.Message, req.Params.Progress, req.Params.Total)
|
||||
},
|
||||
})
|
||||
ctx := context.Background()
|
||||
t1, t2 := mcp.NewInMemoryTransports()
|
||||
if _, err := server.Connect(ctx, t1, nil); err != nil {
|
||||
log.Fatal(err)
|
||||
}
|
||||
|
||||
session, err := client.Connect(ctx, t2, nil)
|
||||
if err != nil {
|
||||
log.Fatal(err)
|
||||
}
|
||||
defer session.Close()
|
||||
if _, err := session.CallTool(ctx, &mcp.CallToolParams{
|
||||
Name: "makeProgress",
|
||||
Meta: mcp.Meta{"progressToken": "abc123"},
|
||||
}); err != nil {
|
||||
log.Fatal(err)
|
||||
}
|
||||
// Output:
|
||||
// frobbing widgets 0/2
|
||||
// frobbing widgets 1/2
|
||||
// frobbing widgets 2/2
|
||||
}
|
||||
```
|
||||
38
docs/server.md
Normal file
38
docs/server.md
Normal file
|
|
@ -0,0 +1,38 @@
|
|||
<!-- Autogenerated by weave; DO NOT EDIT -->
|
||||
# Support for MCP server features
|
||||
|
||||
1. [Prompts](#prompts)
|
||||
1. [Resources](#resources)
|
||||
1. [Tools](#tools)
|
||||
1. [Utilities](#utilities)
|
||||
1. [Completion](#completion)
|
||||
1. [Logging](#logging)
|
||||
1. [Pagination](#pagination)
|
||||
|
||||
## Prompts
|
||||
|
||||
<!-- TODO -->
|
||||
|
||||
## Resources
|
||||
|
||||
<!-- TODO -->
|
||||
|
||||
## Tools
|
||||
|
||||
<!-- TODO -->
|
||||
|
||||
## Utilities
|
||||
|
||||
<!-- TODO -->
|
||||
|
||||
### Completion
|
||||
|
||||
<!-- TODO -->
|
||||
|
||||
### Logging
|
||||
|
||||
<!-- TODO -->
|
||||
|
||||
### Pagination
|
||||
|
||||
<!-- TODO -->
|
||||
90
docs/troubleshooting.md
Normal file
90
docs/troubleshooting.md
Normal file
|
|
@ -0,0 +1,90 @@
|
|||
<!-- Autogenerated by weave; DO NOT EDIT -->
|
||||
# Troubleshooting
|
||||
|
||||
The Model Context Protocol is a complicated spec that leaves some room for
|
||||
interpretation. Client and server SDKs can behave differently, or can be more
|
||||
or less strict about their inputs. And of course, bugs happen.
|
||||
|
||||
When you encounter a problem using the Go SDK, these instructions can help
|
||||
collect information that will be useful in debugging. Please try to provide
|
||||
this information in a bug report, so that maintainers can more quickly
|
||||
understand what's going wrong.
|
||||
|
||||
And most of all, please do [file bugs](https://github.com/modelcontextprotocol/go-sdk/issues/new?template=bug_report.md).
|
||||
|
||||
## Using the MCP inspector
|
||||
|
||||
To debug an MCP server, you can use the [MCP
|
||||
inspector](https://modelcontextprotocol.io/legacy/tools/inspector). This is
|
||||
useful for testing your server and verifying that it works with the typescript
|
||||
SDK, as well as inspecting MCP traffic.
|
||||
|
||||
## Collecting MCP logs
|
||||
|
||||
For [stdio](protocol.md#stdio-transport) transport connections, you can also
|
||||
inspect MCP traffic using a `LoggingTransport`:
|
||||
|
||||
```go
|
||||
func ExampleLoggingTransport() {
|
||||
ctx := context.Background()
|
||||
t1, t2 := mcp.NewInMemoryTransports()
|
||||
server := mcp.NewServer(&mcp.Implementation{Name: "server", Version: "v0.0.1"}, nil)
|
||||
if _, err := server.Connect(ctx, t1, nil); err != nil {
|
||||
log.Fatal(err)
|
||||
}
|
||||
|
||||
client := mcp.NewClient(&mcp.Implementation{Name: "client", Version: "v0.0.1"}, nil)
|
||||
var b bytes.Buffer
|
||||
logTransport := &mcp.LoggingTransport{Transport: t2, Writer: &b}
|
||||
if _, err := client.Connect(ctx, logTransport, nil); err != nil {
|
||||
log.Fatal(err)
|
||||
}
|
||||
fmt.Println(b.String())
|
||||
// Output:
|
||||
// write: {"jsonrpc":"2.0","id":1,"method":"initialize","params":{"capabilities":{"roots":{"listChanged":true}},"clientInfo":{"name":"client","version":"v0.0.1"},"protocolVersion":"2025-06-18"}}
|
||||
// read: {"jsonrpc":"2.0","id":1,"result":{"capabilities":{"logging":{}},"protocolVersion":"2025-06-18","serverInfo":{"name":"server","version":"v0.0.1"}}}
|
||||
// write: {"jsonrpc":"2.0","method":"notifications/initialized","params":{}}
|
||||
|
||||
}
|
||||
```
|
||||
|
||||
That example uses a `bytes.Buffer`, but you can also log to a file, or to
|
||||
`os.Stderr`.
|
||||
|
||||
## Inspecting HTTP traffic
|
||||
|
||||
There are a couple different ways to investigate traffic to an HTTP transport
|
||||
([streamable](protocol.md#streamable-transport) or legacy SSE).
|
||||
|
||||
The first is to use an HTTP middleware:
|
||||
|
||||
```go
|
||||
func ExampleStreamableHTTPHandler_middleware() {
|
||||
server := mcp.NewServer(&mcp.Implementation{Name: "server", Version: "v0.1.0"}, nil)
|
||||
handler := mcp.NewStreamableHTTPHandler(func(r *http.Request) *mcp.Server {
|
||||
return server
|
||||
}, nil)
|
||||
loggingHandler := http.HandlerFunc(func(w http.ResponseWriter, req *http.Request) {
|
||||
// Example debugging; you could also capture the response.
|
||||
body, err := io.ReadAll(req.Body)
|
||||
if err != nil {
|
||||
log.Fatal(err)
|
||||
}
|
||||
req.Body.Close() // ignore error
|
||||
req.Body = io.NopCloser(bytes.NewBuffer(body))
|
||||
fmt.Println(req.Method, string(body))
|
||||
handler.ServeHTTP(w, req)
|
||||
})
|
||||
httpServer := httptest.NewServer(loggingHandler)
|
||||
defer httpServer.Close()
|
||||
|
||||
// The SDK is currently permissive of some missing keys in "params".
|
||||
mustPostMessage(`{"jsonrpc": "2.0", "id": 1, "method":"initialize", "params": {}}`, httpServer.URL)
|
||||
// Output:
|
||||
// POST {"jsonrpc": "2.0", "id": 1, "method":"initialize", "params": {}}
|
||||
}
|
||||
```
|
||||
|
||||
The second is to use a general purpose tool to inspect http traffic, such as
|
||||
[wireshark](https://www.wireshark.org/) or
|
||||
[tcpdump](https://linux.die.net/man/8/tcpdump).
|
||||
Loading…
Reference in a new issue