Fix issue with prompt serialization

examples/readme_server/readme_server.go

@@ -0,0 +1,48 @@
+package main
+
+import (
+	"fmt"
+	"github.com/metoro-io/mcp-golang"
+	"github.com/metoro-io/mcp-golang/transport/stdio"
+)
+
+// Tool arguments are just structs, annotated with jsonschema tags
+// More at https://mcpgolang.com/tools#schema-generation
+type Content struct {
+	Title       string  `json:"title" jsonschema:"required,description=The title to submit"`
+	Description *string `json:"description" jsonschema:"description=The description to submit"`
+}
+type MyFunctionsArguments struct {
+	Submitter string  `json:"submitter" jsonschema:"required,description=The name of the thing calling this tool (openai, google, claude, etc)"`
+	Content   Content `json:"content" jsonschema:"required,description=The content of the message"`
+}
+
+func main() {
+	done := make(chan struct{})
+
+	server := mcp_golang.NewServer(stdio.NewStdioServerTransport())
+	err := server.RegisterTool("hello", "Say hello to a person", func(arguments MyFunctionsArguments) (*mcp_golang.ToolResponse, error) {
+		return mcp_golang.NewToolResponse(mcp_golang.NewTextContent(fmt.Sprintf("Hello, %server!", arguments.Submitter))), nil
+	})
+	if err != nil {
+		panic(err)
+	}
+
+	err = server.RegisterPrompt("promt_test", "This is a test prompt", func(arguments Content) (*mcp_golang.PromptResponse, error) {
+		return mcp_golang.NewPromptResponse("description", mcp_golang.NewPromptMessage(mcp_golang.NewTextContent(fmt.Sprintf("Hello, %server!", arguments.Title)), mcp_golang.RoleUser)), nil
+	})
+	if err != nil {
+		panic(err)
+	}
+
+	err = server.RegisterResource("test://resource", "resource_test", "This is a test resource", "application/json", func() (*mcp_golang.ResourceResponse, error) {
+		return mcp_golang.NewResourceResponse(mcp_golang.NewTextEmbeddedResource("test://resource", "This is a test resource", "application/json")), nil
+	})
+
+	err = server.Serve()
+	if err != nil {
+		panic(err)
+	}
+
+	<-done
+}

internal/protocol/protocol.go

@@ -251,6 +251,7 @@ func (p *Protocol) handleRequest(request *transport.BaseJSONRPCRequest) {
 			if p.FallbackRequestHandler != nil {
 				return p.FallbackRequestHandler(req)
 			}
+			println("no handler for method and no default handler:", req.Method)
 			return nil, fmt.Errorf("method not found: %s", req.Method)
 		}
 	}
@@ -271,14 +272,14 @@ func (p *Protocol) handleRequest(request *transport.BaseJSONRPCRequest) {
 
 		result, err := handler(request, RequestHandlerExtra{Context: ctx})
 		if err != nil {
-			//println("error:", err.Error())
+			println("error:", err.Error())
 			p.sendErrorResponse(request.Id, err)
 			return
 		}
 
 		jsonResult, err := json.Marshal(result)
 		if err != nil {
-			//println("error:", err.Error())
+			println("error:", err.Error())
 			p.sendErrorResponse(request.Id, fmt.Errorf("failed to marshal result: %w", err))
 			return
 		}
@@ -289,6 +290,7 @@ func (p *Protocol) handleRequest(request *transport.BaseJSONRPCRequest) {
 		}
 
 		if err := p.transport.Send(transport.NewBaseMessageResponse(response)); err != nil {
+			println("error:", err.Error())
 			p.handleError(fmt.Errorf("failed to send response: %w", err))
 		}
 	}()

server.go

@@ -94,7 +94,7 @@ func (c promptResponseSent) MarshalJSON() ([]byte, error) {
 		errorText := c.Error.Error()
 		c.Response = NewPromptResponse("error", NewPromptMessage(NewTextContent(errorText), RoleUser))
 	}
-	return json.Marshal(c)
+	return json.Marshal(c.Response)
 }
 
 type Server struct {

transport/stdio/internal/stdio/stdio.go

@@ -102,7 +102,7 @@ func (rb *ReadBuffer) ReadMessage() (*transport.BaseJsonRpcMessage, error) {
 		if rb.buffer[i] == '\n' {
 			// Extract line
 			line := string(rb.buffer[:i])
-			println("read line: ", line)
+			//println("read line: ", line)
 			rb.buffer = rb.buffer[i+1:]
 			return deserializeMessage(line)
 		}
@@ -131,16 +131,22 @@ func deserializeMessage(line string) (*transport.BaseJsonRpcMessage, error) {
 	var notification transport.BaseJSONRPCNotification
 	if err := json.Unmarshal([]byte(line), &notification); err == nil {
 		return transport.NewBaseMessageNotification(&notification), nil
+	} else {
+		//println("unmarshaled notification error:", err.Error())
 	}
 
 	var response transport.BaseJSONRPCResponse
 	if err := json.Unmarshal([]byte(line), &response); err == nil {
 		return transport.NewBaseMessageResponse(&response), nil
+	} else {
+		//println("unmarshaled response error:", err.Error())
 	}
 
 	var errorResponse transport.BaseJSONRPCError
 	if err := json.Unmarshal([]byte(line), &errorResponse); err == nil {
 		return transport.NewBaseMessageError(&errorResponse), nil
+	} else {
+		//println("unmarshaled error response error:", err.Error())
 	}
 
 	// Must be a response

transport/stdio/stdio_server.go

@@ -73,7 +73,7 @@ func (t *StdioServerTransport) Send(message *transport.BaseJsonRpcMessage) error
 	}
 	data = append(data, '\n')
 
-	println("serialized message:", string(data))
+	//println("serialized message:", string(data))
 
 	t.mu.Lock()
 	defer t.mu.Unlock()

transport/types.go

@@ -72,8 +72,9 @@ func (m *BaseJSONRPCRequest) UnmarshalJSON(data []byte) error {
 		return errors.New("field method in BaseJSONRPCRequest: required")
 	}
 	if required.Params == nil {
-		return errors.New("field params in BaseJSONRPCRequest: required")
+		required.Params = new(json.RawMessage)
 	}
+
 	m.Id = *required.Id
 	m.Jsonrpc = *required.Jsonrpc
 	m.Method = *required.Method