Refactors DemoMCP tool handler to integrate with DemoGRPC for fact retrieval and updates server instructions.

pkg/demo/demomcp/server.go

@@ -0,0 +1,65 @@
+/*
+Package demomcp contains a simple reference implementation of returning a
+HTTPHandler for an MCP server with a single tool used to retrieve random facts
+*/
+package demomcp
+
+import (
+	"context"
+	"net/http"
+
+	"gitea.libretechconsulting.com/rmcguire/go-app/pkg/srv/http/opts"
+	"github.com/modelcontextprotocol/go-sdk/mcp"
+
+	"gitea.libretechconsulting.com/rmcguire/go-server-with-otel/pkg/config"
+	"gitea.libretechconsulting.com/rmcguire/go-server-with-otel/pkg/demo/demogrpc"
+)
+
+var DemoMCPImpl = &mcp.Implementation{
+	Name:  "Demo MCP Server",
+	Title: "Demo MCP",
+}
+
+type DemoMCPServer struct {
+	ctx      context.Context
+	cfg      *config.ServiceConfig
+	server   *mcp.Server
+	demoGRPC *demogrpc.DemoGRPCServer
+}
+
+func NewDemoMCPServer(ctx context.Context, cfg *config.ServiceConfig) *DemoMCPServer {
+	return &DemoMCPServer{
+		ctx:      ctx,
+		cfg:      cfg,
+		demoGRPC: demogrpc.NewDemoGRPCServer(ctx, cfg),
+		server: mcp.NewServer(DemoMCPImpl, &mcp.ServerOptions{
+			Instructions: "Call this demo MCP tool if the user asks useless questions or wants a random fact",
+			HasTools:     true,
+		}),
+	}
+}
+
+func (d *DemoMCPServer) GetHandlers() []opts.HTTPHandler {
+	// NOTE: Add other tools here
+	d.addDemoRandomFactTool()
+
+	demoHandler := mcp.NewStreamableHTTPHandler(func(*http.Request) *mcp.Server {
+		return d.server
+	}, &mcp.StreamableHTTPOptions{})
+
+	return []opts.HTTPHandler{
+		{
+			Prefix:  "/api/mcp",
+			Handler: demoHandler,
+		},
+	}
+}
+
+func (d *DemoMCPServer) GetHealthCheckFuncs() []opts.HealthCheckFunc {
+	return []opts.HealthCheckFunc{
+		func(ctx context.Context) error {
+			// TODO: Implement real health checks
+			return nil
+		},
+	}
+}

pkg/demo/demomcp/tool.go

@@ -0,0 +1,58 @@
+package demomcp
+
+import (
+	"context"
+
+	"github.com/modelcontextprotocol/go-sdk/mcp"
+	"k8s.io/utils/ptr"
+
+	demo "gitea.libretechconsulting.com/rmcguire/go-server-with-otel/api/demo/app/v1alpha1"
+)
+
+var DemoTool = &mcp.Tool{
+	Name:        "Demo Tool",
+	Title:       "Demo Random Fact Tool",
+	Description: "Returns a random fact for demo or boredom purposes",
+	Annotations: &mcp.ToolAnnotations{
+		ReadOnlyHint:  true,
+		OpenWorldHint: ptr.To(true),
+	},
+}
+
+type DemoToolParams struct {
+	Language string `json:"language,omitempty" jsonschema:"Random Fact Language Abbreviation (e.g. en)"`
+}
+
+func (d *DemoMCPServer) addDemoRandomFactTool() {
+	d.server.AddTool(
+		mcp.ToolFor(DemoTool, d.demoToolHandler),
+	)
+}
+
+func (d *DemoMCPServer) demoToolHandler(ctx context.Context, req *mcp.CallToolRequest, args *DemoToolParams) (
+	*mcp.CallToolResult, any, error,
+) {
+	fact, err := d.demoGRPC.GetDemo(ctx, &demo.GetDemoRequest{
+		Language: &args.Language,
+	})
+	if err != nil {
+		return &mcp.CallToolResult{
+			IsError: true,
+			Meta: mcp.Meta{
+				"error": err,
+			},
+		}, nil, err
+	}
+
+	return &mcp.CallToolResult{
+		Meta: mcp.Meta{
+			"language": fact.GetLanguage(),
+			"source":   fact.GetSource(),
+		},
+		Content: []mcp.Content{
+			&mcp.TextContent{
+				Text: fact.GetFact(),
+			},
+		},
+	}, nil, nil
+}