f211cc8e4a
CallToolParams.Arguments is any. Clients can send whatever they want. Tool authors who create their own ToolHandler (bypassing NewTool) will receive the arguments as a map[string]any which has been validated against the input schema. Tool authors who call NewTool can choose the type that the arguments unmarshal into. There is no double-unmarshaling and no downcasting. There is no way for tool authors to avoid the unmarshal, and no way to avoid the validation unless the omit an input schema, which is probably bad for LLMs. If tool authors want this optimization, we can provide it later. Change-Id: Ieb201e56c7fb8a23bb1a93b27e946630ec9e79ad Reviewed-on: https://go-review.googlesource.com/c/tools/+/679595 TryBot-Bypass: Jonathan Amsterdam <jba@google.com> Auto-Submit: Jonathan Amsterdam <jba@google.com> Reviewed-by: Robert Findley <rfindley@google.com>
91 lines
2.5 KiB
Go
91 lines
2.5 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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"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 SSE 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[any], error) {
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return &mcp.CallToolResultFor[any]{
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Content: []*mcp.Content{
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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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func PromptHi(ctx context.Context, ss *mcp.ServerSession, args *HiArgs, 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.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.NewTool("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.NewPrompt("greet", "", PromptHi))
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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.NewSSEHandler(func(*http.Request) *mcp.Server {
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return server
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})
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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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fmt.Fprintf(os.Stderr, "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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