npm-mcp

Instructions

Implementation Reference

• src/index.ts:661-689 (handler)

  The "diff" tool is defined and implemented here using `server.tool`. It takes input parameters for package specifications and path, constructs the npm command arguments, executes it using the `run` helper function, and returns the result.

  // ── npm diff ──
  server.tool(
    "diff",
    "Show diff between package versions or between local and registry",
    {
      package: z.string().optional().describe("Package spec for comparison (e.g. pkg@1.0.0..pkg@2.0.0)"),
      specs: z.array(z.string()).optional().describe("Two package specs to compare (e.g. ['pkg@1.0.0', 'pkg@2.0.0'])"),
      path: z.string().optional().describe("Absolute path to local package (compares local vs registry)"),
      diffNameOnly: z.boolean().optional().describe("Only show file names that changed"),
    },
    async ({ package: pkg, specs, path, diffNameOnly }) => {
      const args = ["diff"];
      if (specs && specs.length > 0) {
        for (const s of specs) args.push(`--diff=${s}`);
      } else if (pkg) {
        args.push(`--diff=${pkg}`);
      }
      if (diffNameOnly) args.push("--diff-name-only");
      try {
        const { stdout } = await run(args, path);
        return { content: [{ type: "text", text: stdout || "No differences found" }] };
      } catch (e: any) {
        return {
          content: [{ type: "text", text: `Error: ${e.stderr || e.message}` }],
          isError: true,
        };
      }
    },
  );