Claude Code / Desktop

This walk-through takes about 3 minutes end-to-end. You'll install the MCP server, complete a one-time device login, and run your first cross-layer stack query.

Prerequisites

• Claude Code (CLI) or Claude Desktop installed.
• Node.js 22 LTS or newer — npx ships with it.
• A ToolCairn account (free tier works). You can create one during the login step below.

Step 1 — Register the MCP server

Pick whichever path matches your client:

claude mcp add toolcairn npx -y @neurynae/toolcairn-mcp

{
  "mcpServers": {
    "toolcairn": {
      "command": "npx",
      "args": ["-y", "@neurynae/toolcairn-mcp"]
    }
  }
}

Step 2 — Sign in (device flow)

On first start the MCP server boots into auth-gate mode with exactly one tool exposed: toolcairn_auth. Ask Claude to log you in:

"Run toolcairn_auth and log me in."

What happens under the hood:

You: "Log me in to ToolCairn."

Claude (using ToolCairn):
  → Calls toolcairn_auth { action: "login" }
  → Prints: "Open https://toolcairn.neurynae.com/device and enter code: ABCD-EFGH"
  → Your browser opens automatically. Confirm the code.
  → CLI polls until your sign-in completes.

After login, restart Claude Code/Desktop — all 14 tools become available.

Credentials are stored at ~/.toolcairn/credentials.json (90-day JWT). For mechanics, see Device Auth Flow.

Step 3 — Your first query

Ask Claude anything where a coordinated tool decision helps:

You: "I'm building a full-stack SaaS with TypeScript, Postgres, and Stripe.
      Give me a recommended stack."

Claude (using ToolCairn):
  → Calls refine_requirement to structure the sub-needs
  → Calls get_stack with { framework, database, auth, payment } sub_needs
  → Returns a 4-tool stack with resolved versions:
      • Next.js 15.1.6 (framework)         — Thriving
      • Prisma 6.2.0 (database)            — Thriving
      • Auth.js 5.0.0-beta.29 (auth)       — Active
      • Stripe 17.5.0 (payment)            — Thriving
  → Ready-to-run: `pnpm add next prisma @auth/prisma-adapter stripe`

The agent will transparently choose between search_tools (single pick), get_stack (multi-layer), check_compatibility (version match), and friends. See the full roster on the MCP Tools overview.

Where to next

• Learn the keyword-sentence pattern to boost stack accuracy.
• Try the scan command on an existing project — it audits your dependency manifest.
• Read get_stack — the flagship tool for building coordinated stacks.