pkg

Instructions

Implementation Reference

• src/index.ts:691-717 (registration)

  Registration of the 'pkg' tool via server.tool() on the McpServer instance

  // ── npm pkg ──
  server.tool(
    "pkg",
    "Manage package.json fields programmatically",
    {
      path: z.string().describe("Absolute path to the package directory"),
      action: z.enum(["get", "set", "delete"]).describe("Action to perform"),
      field: z.string().describe("Field name (e.g. 'name', 'scripts.build', 'keywords')"),
      value: z.string().optional().describe("Value to set (required for set action, use JSON for objects/arrays)"),
    },
    async ({ path, action, field, value }) => {
      const args = ["pkg", action, field];
      if (action === "set" && value !== undefined) {
        args.push(value);
      }
      args.push("--json");
      try {
        const { stdout, stderr } = await run(args, path);
        return { content: [{ type: "text", text: stdout + stderr || "Done" }] };
      } catch (e: any) {
        return {
          content: [{ type: "text", text: `Error: ${e.stderr || e.message}` }],
          isError: true,
        };
      }
    },
  );

• src/index.ts:695-700 (schema)

  Zod schema definitions for the 'pkg' tool inputs: path (string), action (enum: get/set/delete), field (string), value (optional string)

  {
    path: z.string().describe("Absolute path to the package directory"),
    action: z.enum(["get", "set", "delete"]).describe("Action to perform"),
    field: z.string().describe("Field name (e.g. 'name', 'scripts.build', 'keywords')"),
    value: z.string().optional().describe("Value to set (required for set action, use JSON for objects/arrays)"),
  },

• src/index.ts:701-717 (handler)

  Handler function for the 'pkg' tool - runs npm pkg command with action, field, and optional value to manage package.json fields programmatically

    async ({ path, action, field, value }) => {
      const args = ["pkg", action, field];
      if (action === "set" && value !== undefined) {
        args.push(value);
      }
      args.push("--json");
      try {
        const { stdout, stderr } = await run(args, path);
        return { content: [{ type: "text", text: stdout + stderr || "Done" }] };
      } catch (e: any) {
        return {
          content: [{ type: "text", text: `Error: ${e.stderr || e.message}` }],
          isError: true,
        };
      }
    },
  );

• src/index.ts:26-38 (helper)

  The run() helper function that executes npm commands via child_process execFile, used by the pkg tool handler

  async function run(
    args: string[],
    cwd?: string,
  ): Promise<{ stdout: string; stderr: string }> {
    const fullArgs = [...args, ...npmrcArgs];
    const opts: { cwd?: string; timeout: number; env: NodeJS.ProcessEnv; maxBuffer: number } = {
      timeout: 120_000,
      maxBuffer: 10 * 1024 * 1024, // 10MB buffer for large outputs
      env: { ...process.env, NO_COLOR: "1" },
    };
    if (cwd) opts.cwd = cwd;
    return exec(NPM, fullArgs, opts);
  }

• src/index.ts:1344-1349 (registration)

  Sandbox registration of the 'pkg' tool (noop implementation) in createSandboxServer()

  sandbox.tool("pkg", "Manage package.json fields programmatically", {
    path: z.string().describe("Absolute path to the package directory"),
    action: z.enum(["get", "set", "delete"]).describe("Action to perform"),
    field: z.string().describe("Field name"),
    value: z.string().optional().describe("Value to set"),
  }, noop);