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agent-mailbox-mcp: Instructions file for Claude Code

CLAUDE.md

agent-mailbox-mcp CLAUDE.md is an instructions file for Claude Code from lleontor705/agent-mailbox-mcp. It costs 1,433 tokens per session, scanned A, original, MIT.

Project instructions for an MCP server that lets software agents exchange messages and provides a web dashboard. MCP is a standard way for AI assistants to call tools, and Vitest is a JavaScript testing tool.

In plain words
What is it for?
Use them to build, type-check, test, inspect, or run the messaging server over command-line or HTTP connections.
Why use it?
They explain the build commands, test setup, database use, transport options, and server structure. This gives the coding agent the context needed to work safely in the repository.

Instructions file for Claude Code

Written for Claude Code: the file is CLAUDE.md. Also seen: mentions CLAUDE.md; mentions Claude Code.

This is lleontor705/agent-mailbox-mcp's own configuration. It tells Claude Code how to work on agent-mailbox-mcp itself, so it is not a mod to install elsewhere. Copy it as a starting point and replace the rules that are about this project. Everything agent-mailbox-mcp configures →

not rated 0repo 4mo ago A scan 1,433 tokens original MIT
View source ↗ lleontor705/agent-mailbox-mcp
Reuse

Borrowing it

Nothing to install: this file belongs to lleontor705/agent-mailbox-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.

Copy the file
curl -O https://raw.githubusercontent.com/lleontor705/agent-mailbox-mcp/main/CLAUDE.md
Clone the repo
git clone --depth 1 https://github.com/lleontor705/agent-mailbox-mcp

Made for: Claude Code.

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Per session 1,433 This file is loaded in full into every session.
When invoked 1,433 The same file — it is already loaded in full.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
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 5.1 $0.01433 $0.01433
Opus 5 $0.00717 $0.00717
Sonnet 5 $0.00287 $0.00287
Haiku 4.5 $0.00143 $0.00143

Measured 9d ago against content hash d5195f5923c8, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-09, from the pricing page.

Security

Grade A, and why

agent-mailbox-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 9d 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.

CLAUDE.md · 102 lines

How it starts

The opening of the file, as written. The whole thing — 102 lines — stays where its author put it; the contents beside it link to each section on GitHub.

CLAUDE.md

This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.

Build & Development Commands

npm run build        # TypeScript compilation to build/
npm run dev          # Run stdio server with tsx (no build step needed)
npm run serve        # Run HTTP server with tsx (dashboard at /dashboard)
npm run lint         # Type-check only (tsc --noEmit)
npm test             # Run all tests once (vitest run)
npm run test:watch   # Watch mode tests
npm run inspect      # Launch MCP inspector for debugging tools

Tests use vitest with globals enabled (no need to import describe/it/expect). Test files live in tests/ and use in-memory SQLite (:memory:). Use initFromDb(db) to set up schema + migrations on a test database.

Architecture

MCP server for inter-agent messaging with A2A protocol support, dual transport (stdio + HTTP), and a web dashboard.

Transport modes (set via MAILBOX_TRANSPORT):

  • stdio (default) — CLI entry (src/index.ts) → StdioServerTransport
  • http — Express entry (src/http.ts) → StreamableHTTPServerTransport on /mcp
  • both — runs both transports simultaneously

HTTP endpoints:

  • /mcp — MCP over HTTP (Streamable HTTP transport with sessions)
  • /a2a — A2A JSON-RPC 2.0 endpoint (tasks/send, tasks/get, tasks/cancel, tasks/respond, tasks/list, push notifications)
  • /a2a/tasks/:id/stream — SSE streaming for task updates
  • /.well-known/agent-card.json — Server Agent Card (A2A discovery)
  • /agents/:id/agent-card.json — Per-agent Agent Card
  • /dashboard — Web dashboard with real-time stats
  • /health — Health check

Request flow: Entry point → transport → createServer() (src/server.ts) → tool handlers → repositories → SQLite

Tool modules (21 MCP tools):

  • src/tools/messaging.ts — 7 tools prefixed msg_* (send, read inbox, broadcast, search, request/reply, threads, count)
  • src/tools/registry.ts — 3 tools (agent_register with A2A Agent Card fields, msg_list_agents, msg_activity_feed)
  • src/tools/a2a.ts — 5 tools prefixed a2a_* (submit_task, get_task, cancel_task, list_tasks, respond_task)
  • src/tools/resources.ts — 3 tools prefixed resource_* (acquire, release, check) for advisory resource leasing
  • src/tools/dead-letter.ts — 3 tools prefixed dlq_* (list, retry, purge) for dead-letter queue management

Read the full file on GitHub · 102 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. 9d ago First seen · 102 lines · 1,433 tokens per session scan A d5195f5923c8

Subscribe to this mod's changes

agent-mailbox-mcp CLAUDE.md is an instructions file published in the GitHub repository lleontor705/agent-mailbox-mcp (0 stars, last pushed 4mo ago), licensed MIT. It adds 1,433 tokens to every session, about $0.0072 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.

Building agentsMulti-Agentaimailboxmcpmessagingmodel-context-protocol
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