Borrowing it
Nothing to install: this file belongs to i11v/fastmail-mcp. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.
curl -O https://raw.githubusercontent.com/i11v/fastmail-mcp/main/CLAUDE.mdgit clone --depth 1 https://github.com/i11v/fastmail-mcpWrote 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.
[](https://agentmods.dev/instructions/i11v/fastmail-mcp/claude-md)<a href="https://agentmods.dev/instructions/i11v/fastmail-mcp/claude-md"><img src="https://agentmods.dev/badge/instructions/i11v/fastmail-mcp/claude-md.svg" alt="Measured on agentmods" height="20"></a>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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00896 | $0.00896 |
| Opus 5 | $0.00448 | $0.00448 |
| Sonnet 5 | $0.00179 | $0.00179 |
| Haiku 4.5 | $0.00090 | $0.00090 |
Grade A, and why
fastmail-mcp CLAUDE.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 7d 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.
How it starts
The opening of the file, as written. The whole thing — 96 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Claude Code Guidelines
Project Overview
Unofficial MCP server for Fastmail integration. Enables AI assistants to interact with Fastmail accounts through the Model Context Protocol for email management, querying, and sending.
- Runtime: Cloudflare Workers
- Deployment: Cloudflare (
wrangler deploy)
Package Manager
Always use pnpm instead of npm for this project.
pnpm install # Install dependencies
pnpm dev # Run local dev server (wrangler)
pnpm run deploy:prod # Deploy to Cloudflare (production)
Quality Commands
pnpm check # Run ALL checks (typecheck + lint + fmt + test)
pnpm typecheck # Type check without compilation
pnpm lint # Lint with oxlint
pnpm lint:fix # Lint and auto-fix
pnpm fmt # Format with oxfmt (write)
pnpm fmt:check # Check formatting without writing
pnpm test # Run tests with vitest
pnpm test:watch # Run tests in watch mode
Always run pnpm check before committing and pushing. Pre-commit hooks (lefthook) enforce format, lint, and typecheck automatically, but pnpm check also runs tests. Never push to remote without all checks passing.
Source Files
src/index.ts- Server setup, Hono routes, MCP initializationsrc/tools.ts- Tool implementations, Zod schemas, JMAP integrationsrc/format.ts- Email formatting for LLM consumption (XML output, HTML→Markdown)src/apps.ts- MCP Apps UI resources and tools (compose_email, read_email)
Tooling
| Tool | Config | Purpose |
|---|---|---|
oxlint |
.oxlintrc.json |
Linting (correctness, suspicious, perf rules) |
oxfmt |
.oxfmtrc.json |
Formatting (Prettier-compatible) |
vitest |
vitest.config.ts |
Testing |
lefthook |
lefthook.yml |
Pre-commit hooks |
typescript |
tsconfig.json |
Type checking (strict mode) |
Key Dependencies
| Package | Purpose |
|---|---|
hono |
Web framework |
@hono/mcp |
MCP integration |
@modelcontextprotocol/sdk |
MCP protocol SDK |
zod |
Schema validation |
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.
- 7d ago First seen · 96 lines · 896 tokens per session scan A bccccb20fc25
fastmail-mcp CLAUDE.md is an instructions file published in the GitHub repository i11v/fastmail-mcp (0 stars, last pushed 3mo ago), licensed MIT. It adds 896 tokens to every session, about $0.0045 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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