feat(logging): enhance logging for metadata extraction and MCP tool handling

internal/mcpserver/schema.go

@@ -3,7 +3,9 @@ package mcpserver
 import (
 	"context"
 	"fmt"
+	"log/slog"
 	"reflect"
+	"time"
 
 	"github.com/google/jsonschema-go/jsonschema"
 	"github.com/google/uuid"
@@ -19,11 +21,39 @@ var toolSchemaOptions = &jsonschema.ForOptions{
 	},
 }
 
-func addTool[In any, Out any](server *mcp.Server, tool *mcp.Tool, handler func(context.Context, *mcp.CallToolRequest, In) (*mcp.CallToolResult, Out, error)) {
+func addTool[In any, Out any](server *mcp.Server, logger *slog.Logger, tool *mcp.Tool, handler func(context.Context, *mcp.CallToolRequest, In) (*mcp.CallToolResult, Out, error)) {
 	if err := setToolSchemas[In, Out](tool); err != nil {
 		panic(fmt.Sprintf("configure MCP tool %q schemas: %v", tool.Name, err))
 	}
-	mcp.AddTool(server, tool, handler)
+	mcp.AddTool(server, tool, logToolCall(logger, tool.Name, handler))
+}
+
+func logToolCall[In any, Out any](logger *slog.Logger, toolName string, handler func(context.Context, *mcp.CallToolRequest, In) (*mcp.CallToolResult, Out, error)) func(context.Context, *mcp.CallToolRequest, In) (*mcp.CallToolResult, Out, error) {
+	if logger == nil {
+		return handler
+	}
+
+	return func(ctx context.Context, req *mcp.CallToolRequest, in In) (*mcp.CallToolResult, Out, error) {
+		start := time.Now()
+		attrs := []any{slog.String("tool", toolName)}
+		if req != nil && req.Params != nil {
+			attrs = append(attrs, slog.Any("arguments", req.Params.Arguments))
+		}
+
+		logger.Info("mcp tool started", attrs...)
+		result, out, err := handler(ctx, req, in)
+
+		completionAttrs := append([]any{}, attrs...)
+		completionAttrs = append(completionAttrs, slog.Duration("duration", time.Since(start)))
+		if err != nil {
+			completionAttrs = append(completionAttrs, slog.String("error", err.Error()))
+			logger.Error("mcp tool completed", completionAttrs...)
+			return result, out, err
+		}
+
+		logger.Info("mcp tool completed", completionAttrs...)
+		return result, out, nil
+	}
 }
 
 func setToolSchemas[In any, Out any](tool *mcp.Tool) error {