feat: introduce context-based Store access and OAuth client listing tool

- Pass the Store instance through MCPServer and set it on the request context for both HTTP and Stdio servers
- Add WithStore and StoreFromContext utilities for context-based Store access
- Implement a new MCP tool for listing OAuth clients in pkg/operation/oauth/client.go
- Register the list_oauth_clients tool in the authentication tools setup

Signed-off-by: appleboy <appleboy.tw@gmail.com>

Author: appleboy

03-oauth-mcp/oauth-server/server.go

@@ -32,11 +32,12 @@ import (
 // MCPServer wraps the underlying MCP server instance.
 type MCPServer struct {
 	server *server.MCPServer
+	store  core.Store
 }
 
 // NewMCPServer creates and configures a new MCPServer instance.
 // Registers the make_authenticated_request and show_auth_token tools.
-func NewMCPServer() *MCPServer {
+func NewMCPServer(store core.Store) *MCPServer {
 	mcpServer := server.NewMCPServer(
 		"example-oauth-server",
 		"1.0.0",
@@ -50,6 +51,7 @@ func NewMCPServer() *MCPServer {
 
 	return &MCPServer{
 		server: mcpServer,
+		store:  store,
 	}
 }
 
@@ -59,6 +61,7 @@ func (s *MCPServer) ServeHTTP() *server.StreamableHTTPServer {
 	return server.NewStreamableHTTPServer(s.server,
 		server.WithHeartbeatInterval(30*time.Second),
 		server.WithHTTPContextFunc(func(ctx context.Context, r *http.Request) context.Context {
+			ctx = core.WithStore(ctx, s.store)
 			ctx = core.AuthFromRequest(ctx, r)
 			return core.WithRequestID(ctx)
 		}),
@@ -69,6 +72,7 @@ func (s *MCPServer) ServeHTTP() *server.StreamableHTTPServer {
 // auth token from the environment into the context.
 func (s *MCPServer) ServeStdio() error {
 	return server.ServeStdio(s.server, server.WithStdioContextFunc(func(ctx context.Context) context.Context {
+		ctx = core.WithStore(ctx, s.store)
 		ctx = core.AuthFromEnv(ctx)
 		return core.WithRequestID(ctx)
 	}))
@@ -152,7 +156,7 @@ func main() {
 		}
 	}
 
-	mcpServer := NewMCPServer()
+	mcpServer := NewMCPServer(oauthStore)
 	router := gin.Default()
 	router.Use(corsMiddleware())
 

pkg/core/core.go

@@ -16,6 +16,9 @@ type AuthKey struct{}
 // RequestIDKey is a custom context key type for storing the request ID in context.
 type RequestIDKey struct{}
 
+// StoreKey is a custom context key type for storing the Store in context.
+type StoreKey struct{}
+
 // WithRequestID returns a new context with a generated request ID set.
 func WithRequestID(ctx context.Context) context.Context {
 	reqID := uuid.New().String()
@@ -59,3 +62,18 @@ func LoggerFromCtx(ctx context.Context) *slog.Logger {
 	}
 	return slog.Default()
 }
+
+// WithStore returns a new context with the provided Store set.
+func WithStore(ctx context.Context, store Store) context.Context {
+	return context.WithValue(ctx, StoreKey{}, store)
+}
+
+// StoreFromContext retrieves the Store from the context.
+// Returns the Store interface if present, or an error if missing.
+func StoreFromContext(ctx context.Context) (Store, error) {
+	store, ok := ctx.Value(StoreKey{}).(Store)
+	if !ok {
+		return nil, fmt.Errorf("missing store")
+	}
+	return store, nil
+}

pkg/operation/oauth/client.go

@@ -0,0 +1,46 @@
+// Package oauth provides MCP tools for managing OAuth clients.
+package oauth
+
+import (
+	"context"
+	"encoding/json"
+
+	"github.com/go-training/mcp-workshop/pkg/core"
+	"github.com/mark3labs/mcp-go/mcp"
+)
+
+// ListOAuthClientsTool defines the MCP tool for listing all OAuth clients.
+var ListOAuthClientsTool = mcp.NewTool("list_oauth_clients",
+	mcp.WithDescription("List all OAuth clients"),
+)
+
+// HandleListOAuthClientsTool is an MCP tool handler that retrieves and returns
+// a list of all registered OAuth clients from the store.
+func HandleListOAuthClientsTool(
+	ctx context.Context,
+	_ mcp.CallToolRequest,
+) (*mcp.CallToolResult, error) {
+	logger := core.LoggerFromCtx(ctx)
+	logger.Info("Handling list_oauth_clients tool")
+
+	store, err := core.StoreFromContext(ctx)
+	if err != nil {
+		logger.Error("Missing store from context", "error", err)
+		return nil, err
+	}
+
+	clients, err := store.GetClients(ctx)
+	if err != nil {
+		logger.Error("Failed to get clients from store", "error", err)
+		return nil, err
+	}
+
+	data, err := json.Marshal(clients)
+	if err != nil {
+		logger.Error("Failed to marshal clients to JSON", "error", err)
+		return nil, err
+	}
+
+	logger.Info("Successfully retrieved OAuth clients")
+	return mcp.NewToolResultText(string(data)), nil
+}

pkg/operation/operation.go

@@ -3,6 +3,7 @@ package operation
 import (
 	"github.com/go-training/mcp-workshop/pkg/operation/caculator"
 	"github.com/go-training/mcp-workshop/pkg/operation/echo"
+	"github.com/go-training/mcp-workshop/pkg/operation/oauth"
 	"github.com/go-training/mcp-workshop/pkg/operation/token"
 
 	"github.com/mark3labs/mcp-go/server"
@@ -50,6 +51,10 @@ func RegisterAuthTool(s *server.MCPServer) {
 		Tool:    token.ShowAuthTokenTool,
 		Handler: token.HandleShowAuthTokenTool,
 	})
+	tool.RegisterRead(server.ServerTool{
+		Tool:    oauth.ListOAuthClientsTool,
+		Handler: oauth.HandleListOAuthClientsTool,
+	})
 
 	s.AddTools(tool.Tools()...)
 }