Borrowing it
Nothing to install: this file belongs to factorial-io/imap-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/factorial-io/imap-mcp/main/CLAUDE.mdgit clone --depth 1 https://github.com/factorial-io/imap-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/factorial-io/imap-mcp/claude-md)<a href="https://agentmods.dev/instructions/factorial-io/imap-mcp/claude-md"><img src="https://agentmods.dev/badge/instructions/factorial-io/imap-mcp/claude-md/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/instructions/factorial-io/imap-mcp/claude-md"><img src="https://agentmods.dev/badge/instructions/factorial-io/imap-mcp/claude-md.svg" alt="Reviewed on agentmods" width="80" 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 | $0.00309 | $0.00309 |
| Opus 5 | $0.00154 | $0.00154 |
| Sonnet 5 | $0.00062 | $0.00062 |
| Haiku 4.5 | $0.00031 | $0.00031 |
Grade A, and why
imap-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 8d 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.
What it actually says
CLAUDE.md
Rust MCP server bridging claude.ai to IMAP email via OIDC auth.
Build & Test
cargo build
cargo test
cargo fmt -- --check
cargo clippy -- -D warnings
Version Control
We use jj (Jujutsu) when available, otherwise plain git.
Error Handling
Never suppress errors with .unwrap(), .expect(), or silent let _ =. Propagate errors using ? and return meaningful errors as late as possible. Use thiserror for typed domain errors and anyhow for ad-hoc context.
Project Layout
src/main.rs— entrypoint, Axum server setupsrc/lib.rs— app config, shared statesrc/auth.rs— OAuth/OIDC flow, dynamic client registration, token exchangesrc/mcp.rs— MCP tool definitions (list_folders, list_emails, get_email, search_emails, mark_read, mark_unread)src/imap.rs— IMAP client operationssrc/session.rs— Redis session storage, encryptionsrc/error.rs— error typessrc/extract.rs— text extraction for attachments (PDF, DOCX, XLSX, PPTX)tests/integration.rs— integration tests
Recent Changes
- 001-limit-attachment-size: Added attachment size limiting and text extraction
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.
- 8d ago First seen · 37 lines · 309 tokens per session scan A eb8d49cb1235
imap-mcp CLAUDE.md is an instructions file published in the GitHub repository factorial-io/imap-mcp (2 stars, last pushed yesterday), licensed MIT. It adds 309 tokens to every session, about $0.0015 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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