Custom Commands

This page shows how to add a new MCP command (tool) to this repo's server.

The MCP server entrypoint is packages/sdk/src/mcp-server.ts, and each tool is registered with server.registerTool(...).

1) Add the command implementation

Create or update a function in packages/sdk/src/tools/.

Example (packages/sdk/src/tools/system.ts):

export function getCurrentTimestamp(): string {
  return new Date().toISOString();
}

2) Register the command in mcp-server.ts

Import the function, then register a tool with:

• A unique tool name
• A clear description
• A zod input schema
• A handler that returns MCP content

Example:

import { z } from "zod";
import { getCurrentTimestamp } from "./tools/system.js";

server.registerTool(
  "getCurrentTimestamp",
  {
    description: "Return current UTC timestamp in ISO-8601 format.",
    inputSchema: {},
  },
  async () => ({
    content: [{ type: "text", text: getCurrentTimestamp() }],
  })
);

For commands that need input, define fields in inputSchema:

inputSchema: {
  directory: z.string().optional().describe("Working directory to inspect."),
}

3) Build the SDK package

From the repo root:

pnpm --filter @repo/sdk build

This updates packages/sdk/dist/mcp-server.js with your new command.

4) Reload your MCP host and test

If you run from source in Cursor, make sure your MCP config points to:

{
  "mcpServers": {
    "@repo/sdk": {
      "command": "node",
      "args": ["/absolute/path/to/claude-cli-MCP/packages/sdk/dist/mcp-server.js"]
    }
  }
}

Then restart Cursor (or reload MCP servers), and call your new tool by name.

Tips

• Keep tool names action-oriented (for example, reviewDiffsBeforeCommit).
• Put complex logic in packages/sdk/src/tools/*, and keep mcp-server.ts focused on registration and transport wiring.
• Log only to stderr in server code. stdout is reserved for MCP JSON-RPC.