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fastmail-mcp AGENTS.md

fastmail-mcp AGENTS.md is an instructions file for Codex, OpenCode from adinschmidt/fastmail-mcp. It costs 1,333 tokens per session, scanned A, original, MIT.

A set of AGENTS.md instructions for a Bun and TypeScript server that connects to mail, calendars, and contacts. AGENTS.md is a file that tells coding agents how a repository should be built, tested, and changed.

In plain words
What is it for?
Use it when working on this server to install dependencies, run checks, build the project, and follow its TypeScript and configuration conventions.
Why use it?
It gives the agent the repository's commands, coding rules, error-handling guidance, and requirements for protecting secrets.

Instructions file for CodexOpenCode

not rated 0 26d ago A scan 1,333 tokens original MIT
View the source file adinschmidt/fastmail-mcp
Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add instructions/adinschmidt/fastmail-mcp/agents-md
Clone the repo
git clone --depth 1 https://github.com/adinschmidt/fastmail-mcp

Made for: Codex, OpenCode.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for fastmail-mcp AGENTS.md

README.md
[![agentmods](https://agentmods.dev/badge/instructions/adinschmidt/fastmail-mcp/agents-md.svg)](https://agentmods.dev/instructions/adinschmidt/fastmail-mcp/agents-md)
Your own site
<a href="https://agentmods.dev/instructions/adinschmidt/fastmail-mcp/agents-md"><img src="https://agentmods.dev/badge/instructions/adinschmidt/fastmail-mcp/agents-md.svg" alt="Measured on agentmods" height="20"></a>
Per session 1,333 This file is loaded in full into every session.
When invoked 1,333 The same file — it is already loaded in full.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.01333 $0.01333
Opus 5 $0.00666 $0.00666
Sonnet 5 $0.00267 $0.00267
Haiku 4.5 $0.00133 $0.00133

Measured 4d ago against content hash 88e5edfaaa20, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

fastmail-mcp AGENTS.md scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 4d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

AGENTS.md · 138 lines

How it starts

The opening of the file, as written. The whole thing — 138 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Agent Instructions

This repo is a Bun + TypeScript MCP server for mail (JMAP) + calendar (CalDAV) + contacts (CardDAV). It is provider-generic; Fastmail works out of the box via legacy FASTMAIL_* env vars (the project began as fastmail-mcp).

Key paths:

  • src/index.ts MCP server + tool registration (domain-gated: mail/calendar/contacts register based on configured credentials or MCP_DOMAINS)
  • src/bin/* mail-only (jmap-mcp) and calendar/contacts-only (dav-mcp) entry points
  • src/jmap/* JMAP auth/client/types
  • src/dav/* CalDAV/CardDAV client helpers + iCal/vCard helpers
  • src/config.ts env var loading — generic JMAP_*/DAV_*/CALDAV_URL/CARDDAV_URL vars with FASTMAIL_* fallbacks that imply Fastmail server URLs

Commands (Build / Lint / Test)

Package manager/runtime:

  • Install deps: bun install (lockfile: bun.lock)
  • Run dev server (watch): bun run dev
  • Run server (stdio): bun run start

Typecheck/build:

  • Typecheck: bun run typecheck
  • Build bundle to dist/: bun run build
  • Clean build output: bun run clean

Lint/format:

  • No linter/formatter is currently configured (no ESLint/Prettier config in repo).
  • Use bun run typecheck as the primary quality gate.
  • If adding a formatter, prefer a repo-pinned tool (devDependency + config) rather than ad-hoc bunx.

Tests:

  • Bun's built-in runner (*.test.ts files in src/):
    • Run all: bun test
    • Run one file: bun test src/calendar-crud.test.ts
    • Run one test by name: bun test -t "parses vCard"
    • Watch: bun test --watch

Code Style (TypeScript / Imports / Formatting)

Module system:

  • ESM + moduleResolution: NodeNext (see tsconfig.json).
  • Local imports MUST use .js extensions in source (TypeScript will map them):
    • Good: import { loadDavConfig } from './config.js'
    • Bad: import { loadDavConfig } from './config'

Imports:

  • Prefer node: protocol for Node built-ins: import { randomUUID } from 'node:crypto'.
  • Import order (keep blocks visually separated):
    1. Node built-ins (node:*)
    2. Third-party deps (zod, tsdav, MCP SDK)
    3. Local modules (./foo.js, ../bar.js)

Read the full file on GitHub · 138 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 4d ago First seen · 138 lines · 1,333 tokens per session scan A 88e5edfaaa20

Subscribe to this mod's changes

fastmail-mcp AGENTS.md is an instructions file published in the GitHub repository adinschmidt/fastmail-mcp (0 stars, last pushed 26d ago), licensed MIT. It adds 1,333 tokens to every session, about $0.0067 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

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