mcp: add a streamable serving benchmark

Add a benchmark using the streamable HTTP handler, and a more realistic input/output signature. Also expose this handler as an example (both a go example and a server in the examples/ directory).

mcp/streamable_bench_test.go

@@ -0,0 +1,66 @@
+// 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_test
+
+import (
+	"context"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+
+	"github.com/google/jsonschema-go/jsonschema"
+	"github.com/modelcontextprotocol/go-sdk/mcp"
+)
+
+func BenchmarkStreamableServing(b *testing.B) {
+	// This benchmark measures how fast we can handle a single tool on a
+	// streamable server, including tool validation and stream management.
+	customSchemas := map[any]*jsonschema.Schema{
+		Probability(0):  {Type: "number", Minimum: jsonschema.Ptr(0.0), Maximum: jsonschema.Ptr(1.0)},
+		WeatherType(""): {Type: "string", Enum: []any{Sunny, PartlyCloudy, Cloudy, Rainy, Snowy}},
+	}
+	opts := &jsonschema.ForOptions{TypeSchemas: customSchemas}
+	in, err := jsonschema.For[WeatherInput](opts)
+	if err != nil {
+		b.Fatal(err)
+	}
+	out, err := jsonschema.For[WeatherOutput](opts)
+	if err != nil {
+		b.Fatal(err)
+	}
+
+	server := mcp.NewServer(&mcp.Implementation{Name: "server", Version: "v0.0.1"}, nil)
+	mcp.AddTool(server, &mcp.Tool{
+		Name:         "weather",
+		InputSchema:  in,
+		OutputSchema: out,
+	}, WeatherTool)
+
+	handler := mcp.NewStreamableHTTPHandler(func(r *http.Request) *mcp.Server {
+		return server
+	}, &mcp.StreamableHTTPOptions{JSONResponse: true})
+	httpServer := httptest.NewServer(handler)
+	defer httpServer.Close()
+
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+	session, err := mcp.NewClient(testImpl, nil).Connect(ctx, &mcp.StreamableClientTransport{Endpoint: httpServer.URL}, nil)
+	if err != nil {
+		b.Fatal(err)
+	}
+	defer session.Close()
+	b.ResetTimer()
+	for range b.N {
+		if _, err := session.CallTool(ctx, &mcp.CallToolParams{
+			Name: "weather",
+			Arguments: WeatherInput{
+				Location: Location{Name: "somewhere"},
+				Days:     7,
+			},
+		}); err != nil {
+			b.Errorf("CallTool failed: %v", err)
+		}
+	}
+}