# The MCP Server Builder's Checklist — 12 Questions to Ship

## Phase 1: Scope Your Server

- [ ] **What tool(s) does your agent need?** — Database query? API call? File system? Search? CRM action?
- [ ] **What's the data format?** — JSON, CSV, plain text, Markdown, binary? Pass schema if structured.
- [ ] **Does it need authentication?** — API key, OAuth, JWT, mTLS? List the credential requirements.
- [ ] **Is there an existing API?** — REST, GraphQL, gRPC? If yes, note the endpoint and auth pattern.
- [ ] **Read-only or read-write?** — If write-capable, define the input validation and idempotency rules.

## Phase 2: Choose Your Stack

- [ ] **Python with FastMCP?** — Use this if you need to ship fast (26.9K★, 585 stars/week). Best for AI agent tooling.
- [ ] **TypeScript with MCP SDK?** — Use if you need to match an existing TS codebase. More type safety, slower to iterate.
- [ ] **Single-file or modular?** — Start single-file for simple tools. Split into modules when you have 3+ tools.

## Phase 3: Build & Test

- [ ] **Run `fastmcp dev` locally** — Test all tools with sample inputs before deploying.
- [ ] **Add error handling** — Wrap every tool call in try/except with descriptive error messages.
- [ ] **Add input validation** — Validate types, ranges, and required fields. MCP clients can't see your Python errors.
- [ ] **Write a test for each tool** — At minimum: happy path, edge case, invalid input. Use pytest + fastmcp test client.

## Phase 4: Deploy

- [ ] **Containerize** — `uv pip install fastmcp && fastmcp run server.py` in a Docker container. Pin dependencies.
- [ ] **Add health endpoint** — MCP servers need a `/health` or `GET /` that returns `{"status":"ok"}`.
- [ ] **Set up auth** — If not public, add API key validation or IP allowlist.
- [ ] **Document for the agent** — Write a `USAGE.md` that tells the agent: what tools exist, what each does, what data it expects, and any pitfalls.

## Scoring

| Score | Status | Action |
|-------|--------|--------|
| 10-12 checks | 🏆 Production-ready | Ship it. Your MCP server is safe, tested, and documented. |
| 7-9 checks | ⚠️ Needs work | Missing auth, tests, or docs. Run the checklist again before deploying. |
| 0-6 checks | 🚨 Prototype only | Do not deploy to production. Scope is unclear and errors will burn the agent. |

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