# Author MCP

> Walk through authoring a kind:mcp DRIVER.md — wraps a Model Context Protocol server (Anthropic-spec) as a conformant driver implementing one or more abstract TOOL contracts.

- Skill: `agentproto/author-mcp` (Agent Skill)
- Install (CLI): `npx skillmds@latest add agentproto/author-mcp`
- Raw SKILL.md: https://api.skillmd.com/api/skills/agentproto/author-mcp/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: AI & ML
- Author: agentproto (https://skillmd.com/u/agentproto)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/agentproto/author-mcp

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# Author an MCP driver (AIP-32)

Use when wrapping an MCP server (local or remote) as a conformant
driver for AIP-14 TOOL contracts. The skill produces a
frontmatter-only DRIVER.md when standard MCP dispatch suffices.

## Process

1. **Identity**: pick `id` ending in `-mcp`, set `name`,
   `description`, `version`, `kind: mcp`.
2. **Server location**: declare `server` per `kind`:
   - `npm` — `package` + `args`
   - `docker` — `image` + `env` (with `${secrets.X}` substitutions)
   - `binary` — `path` + `args`
   - `remote` — `url`
3. **Transport**: `stdio` for local subprocess, `sse` for streaming
   remote, `http` for request-response remote.
4. **Connect once** (during authoring) and run `tools/list` to
   discover available MCP tool names.
5. **Map TOOLs**: for each contract-to-implement, pick the matching
   MCP tool name. Author `metadata.mcp.tool_name`,
   `argument_mapping` (when contract input keys differ from MCP arg
   names), `result_extract` (when MCP response wraps the contract
   output).
6. **Auth**: if the server needs secrets, declare in `auth.ref` →
   sibling SECRETS.md, with `auth.state.env` listing required env
   vars. For local servers, secrets are passed via `server.env`.
   For remote servers, auth is HTTP-style.
7. **Sandbox**: `network.egress` for remote, `[]` for local.
   `policy_tags` (self-hosted, third-party-api).
8. **Optional integration**: declare `prompts[]` for skill_block
   integration and `resources[]` for ref_kind integration.
9. **Validate** against `MCP.schema.json` AND `DRIVER.schema.json`.
10. **Wire**: `loadProvider(...)`; the runtime spawns/connects on
    first call, lists tools, validates declared `tool_name`s exist.

## Common mistakes

- **Hardcoded paths in stdio servers** — vendored binaries are
  workspace-relative; document this in `server.path`.
- **Missing `tool_name` validation** — server-supplied schemas must
  match the contract; mismatches MUST fail at registration, not at
  first call.
- **Long-lived stdio process leaking tenant state** — pass tenant
  context in `tools/call.arguments`, never bind at spawn.
- **Remote MCP without TLS** — refuse `http://` URLs in production.