MCP Troubleshooter

Implementation Reference

• src/index.ts:331-370 (handler)

  The handler function for the 'update-mcp-config' tool. Validates the input JSON string, backs up the existing Claude Desktop configuration file if it exists, ensures the config directory is present, writes the new configuration to the platform-specific path, and returns a success message or error details.

  async ({ config }) => {
    try {
      // Validate the JSON
      try {
        JSON.parse(config);
      } catch (error) {
        return {
          isError: true,
          content: [{ type: "text", text: `Invalid JSON configuration: ${error.message}` }]
        };
      }
  
      // Create backup of existing config if it exists
      try {
        const existingConfig = await fs.readFile(configPath, 'utf-8');
        const backupPath = `${configPath}.backup.${Date.now()}`;
        await fs.writeFile(backupPath, existingConfig);
      } catch (error) {
        // Ignore if no existing config
      }
  
      // Ensure directory exists
      await fs.mkdir(path.dirname(configPath), { recursive: true });
      
      // Write new config
      await fs.writeFile(configPath, config);
      
      return {
        content: [{ 
          type: "text", 
          text: `Configuration successfully updated at ${configPath}.\n\nNote: You'll need to restart Claude Desktop for changes to take effect.` 
        }]
      };
    } catch (error) {
      return {
        isError: true,
        content: [{ type: "text", text: `Error updating configuration: ${error.message}` }]
      };
    }
  }

• src/index.ts:328-330 (schema)

  The Zod input schema for the 'update-mcp-config' tool, defining a single 'config' parameter as a string containing the full JSON configuration to write to the file.

  {
    config: z.string().describe("JSON configuration to write (entire file content)")
  },

• src/index.ts:326-371 (registration)

  The registration of the 'update-mcp-config' tool on the MCP server instance using server.tool(), specifying the tool name, input schema, and handler function.

  server.tool(
    "update-mcp-config",
    {
      config: z.string().describe("JSON configuration to write (entire file content)")
    },
    async ({ config }) => {
      try {
        // Validate the JSON
        try {
          JSON.parse(config);
        } catch (error) {
          return {
            isError: true,
            content: [{ type: "text", text: `Invalid JSON configuration: ${error.message}` }]
          };
        }
  
        // Create backup of existing config if it exists
        try {
          const existingConfig = await fs.readFile(configPath, 'utf-8');
          const backupPath = `${configPath}.backup.${Date.now()}`;
          await fs.writeFile(backupPath, existingConfig);
        } catch (error) {
          // Ignore if no existing config
        }
  
        // Ensure directory exists
        await fs.mkdir(path.dirname(configPath), { recursive: true });
        
        // Write new config
        await fs.writeFile(configPath, config);
        
        return {
          content: [{ 
            type: "text", 
            text: `Configuration successfully updated at ${configPath}.\n\nNote: You'll need to restart Claude Desktop for changes to take effect.` 
          }]
        };
      } catch (error) {
        return {
          isError: true,
          content: [{ type: "text", text: `Error updating configuration: ${error.message}` }]
        };
      }
    }
  );