Add MCP Tool

This skill explains how to Register a new tool in the MCP server so it can be used by LLMs.

Prerequisites

The functionality must already exist in a Service (e.g., csfd.movie(id)). If not, use the implement_scraper_feature skill first.

1. LOCATE the Server Entry

•File: mcp-server/index.ts

2. DEFINE Input Schema

Use Zod to define the input arguments. Rule: Every .describe() call is part of the prompt for the AI. Be descriptive!

typescript

const toolArgs = {
  myParam: z.string().describe('Description of what this parameter does...')
};

3. REGISTER the Tool

Add the server.tool() call.

typescript

server.tool(
  'tool_name_snake_case',
  'A clear, action-oriented description of what the tool does. Mention required inputs.',
  toolArgs,
  async ({ myParam }) => {
    try {
      // 1. Call the service
      const result = await csfd.someMethod(myParam);

      // 2. Return JSON content
      return {
        content: [
          {
            type: 'text',
            text: JSON.stringify(result, null, 2)
          }
        ]
      };
    } catch (error) {
      // 3. Handle errors gracefully
      return {
        content: [{ type: 'text', text: `Error: ${error}` }],
        isError: true
      };
    }
  }
);

4. TEST the Tool

•Command: yarn build:mcp (to check types)
•Manual Test: You can temporarily add a call to main() or use the MCP Inspector if configured.