3da831b0c9* mcp: move to 2025-06-18 schema Add types and fields for the latest MCP schema. The main challenge here was dealing with the presence of _meta fields on many types, like Tool, Prompt and Resource. - Distinguish between the _meta field of a request's params, which includes a progress token, from the _meta field on other types, which is simply a map. - Redefine GetMeta to return a pointer to the map. We wanted to avoid that, but I don't see a clean way to do so. An alternative would be to have GetMeta return a map, and SetMeta to set it. - Provide GetProgressToken for requests only (not notifications or other types). - Still to do: deal with the meta and annotation fields of ContentBlock, which are currently duplicated for Resource and ResourceContents. * Meta and progress token redesign
98 lines
2.7 KiB
Go
98 lines
2.7 KiB
Go
// Copyright 2025 The Go MCP SDK Authors. All rights reserved.
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// Use of this source code is governed by an MIT-style
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// license that can be found in the LICENSE file.
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package main
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import (
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"context"
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"flag"
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"fmt"
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"log"
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"net/http"
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"net/url"
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"os"
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"github.com/modelcontextprotocol/go-sdk/mcp"
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)
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var httpAddr = flag.String("http", "", "if set, use streamable HTTP at this address, instead of stdin/stdout")
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type HiArgs struct {
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Name string `json:"name"`
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}
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func SayHi(ctx context.Context, ss *mcp.ServerSession, params *mcp.CallToolParamsFor[HiArgs]) (*mcp.CallToolResultFor[struct{}], error) {
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return &mcp.CallToolResultFor[struct{}]{
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Content: []*mcp.ContentBlock{
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mcp.NewTextContent("Hi " + params.Name),
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},
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}, nil
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}
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// TODO(jba): it should be OK for args to be a pointer, but this fails in
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// jsonschema. Needs investigation.
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func PromptHi(ctx context.Context, ss *mcp.ServerSession, params *mcp.GetPromptParams) (*mcp.GetPromptResult, error) {
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return &mcp.GetPromptResult{
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Description: "Code review prompt",
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Messages: []*mcp.PromptMessage{
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{Role: "user", Content: mcp.NewTextContent("Say hi to " + params.Arguments["name"])},
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},
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}, nil
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}
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func main() {
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flag.Parse()
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server := mcp.NewServer("greeter", "v0.0.1", nil)
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server.AddTools(mcp.NewServerTool("greet", "say hi", SayHi, mcp.Input(
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mcp.Property("name", mcp.Description("the name to say hi to")),
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)))
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server.AddPrompts(&mcp.ServerPrompt{
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Prompt: &mcp.Prompt{Name: "greet"},
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Handler: PromptHi,
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})
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server.AddResources(&mcp.ServerResource{
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Resource: &mcp.Resource{
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Name: "info",
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MIMEType: "text/plain",
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URI: "embedded:info",
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},
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Handler: handleEmbeddedResource,
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})
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if *httpAddr != "" {
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handler := mcp.NewStreamableHTTPHandler(func(*http.Request) *mcp.Server {
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return server
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}, nil)
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log.Printf("MCP handler listening at %s", *httpAddr)
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http.ListenAndServe(*httpAddr, handler)
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} else {
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t := mcp.NewLoggingTransport(mcp.NewStdioTransport(), os.Stderr)
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if err := server.Run(context.Background(), t); err != nil {
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log.Printf("Server failed: %v", err)
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}
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}
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}
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var embeddedResources = map[string]string{
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"info": "This is the hello example server.",
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}
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func handleEmbeddedResource(_ context.Context, _ *mcp.ServerSession, params *mcp.ReadResourceParams) (*mcp.ReadResourceResult, error) {
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u, err := url.Parse(params.URI)
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if err != nil {
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return nil, err
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}
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if u.Scheme != "embedded" {
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return nil, fmt.Errorf("wrong scheme: %q", u.Scheme)
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}
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key := u.Opaque
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text, ok := embeddedResources[key]
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if !ok {
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return nil, fmt.Errorf("no embedded resource named %q", key)
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}
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return &mcp.ReadResourceResult{
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Contents: []*mcp.ResourceContents{mcp.NewTextResourceContents(params.URI, "text/plain", text)},
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}, nil
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}
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