internal/mcp: fix prompt example

The hello example was using params.Name, which is the name of the
prompt. It should use args.Name.

Change-Id: I0e7e992bbe312fd5a6e56e9bc46a931f0eeb423c
Reviewed-on: https://go-review.googlesource.com/c/tools/+/682416
Reviewed-by: Robert Findley <[email protected]>
Reviewed-by: Sam Thanawalla <[email protected]>
LUCI-TryBot-Result: Go LUCI <[email protected]>

Author: jba

internal/mcp/examples/hello/main.go

@@ -32,11 +32,11 @@ func SayHi(ctx context.Context, ss *mcp.ServerSession, params *mcp.CallToolParam
 
 // TODO(jba): it should be OK for args to be a pointer, but this fails in
 // jsonschema. Needs investigation.
-func PromptHi(ctx context.Context, ss *mcp.ServerSession, args HiArgs, params *mcp.GetPromptParams) (*mcp.GetPromptResult, error) {
+func PromptHi(ctx context.Context, ss *mcp.ServerSession, args HiArgs, _ *mcp.GetPromptParams) (*mcp.GetPromptResult, error) {
 	return &mcp.GetPromptResult{
 		Description: "Code review prompt",
 		Messages: []*mcp.PromptMessage{
-			{Role: "user", Content: mcp.NewTextContent("Say hi to " + params.Name)},
+			{Role: "user", Content: mcp.NewTextContent("Say hi to " + args.Name)},
 		},
 	}, nil
 }

internal/mcp/prompt.go

@@ -75,11 +75,11 @@ func NewServerPrompt[In any](name, description string, handler func(context.Cont
 		if err != nil {
 			return nil, err
 		}
-		var v In
-		if err := unmarshalSchema(rawArgs, resolved, &v); err != nil {
+		var args In
+		if err := unmarshalSchema(rawArgs, resolved, &args); err != nil {
 			return nil, err
 		}
-		return handler(ctx, ss, v, params)
+		return handler(ctx, ss, args, params)
 	}
 	for _, opt := range opts {
 		opt.set(prompt)