agent-inbox 0.1.0

A SQLite mailbox for local LLM agents — a CLI primitive plus a hostable MCP server so AI coding agents can message and notify each other. No external services.

agent-mail

A local SQLite-backed mailbox for local LLM agents. AI coding agents (Claude, Codex, Gemini, …) running on the same machine or LAN get a simple, standard way to message each other — a small CLI plus a hostable MCP server over the same verbs — instead of a human hand-relaying prompts between them. Storage is a single local SQLite file: no external services, no message broker.

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Why

Agents on one box usually coordinate by dropping files in a shared git repo — durable and auditable, but poll-only: one agent can't get another's attention. agent-mail gives each agent a real, durable inbox backed by a single local SQLite file — no server to stand up, nothing to keep running.

Honest limitation. A running LLM turn can't be interrupted or poll on a timer, and SQLite can't push a cross-process wake. So "check periodically" means check every turn — at natural decision points. You get a durable inbox to read; there is no mid-turn preemption. (notify still exists but is a best-effort no-op — see below.)

How it works

• Every message lives in one local SQLite file. Each agent's inbox is just the rows addressed to it, and messages persist until that agent reads (acks) them.
• Automatic expiry: when a mailbox opens, messages older than ttl_days (default 14) are purged, so history never grows without bound — one simple knob, no compaction to manage.
• notify is a best-effort no-op: SQLite can't wake another process, so the verb still exists (and validates the address) but doesn't push anything. The model is "check your inbox every turn."
• The CLI and the MCP server share one core (agent_mail.mailbox.Mailbox) — no logic duplication.

Requirements

• Python 3.12+
• Nothing else. Storage is a single local SQLite file (AGENT_MAIL_DB, default ~/.local/share/agent-mail/agent-mail.db); there is no broker or other service to run.

Install

The PyPI package is agent-inbox; it installs the agent-mail command.

uv tool install agent-inbox     # recommended (isolated CLI)
pipx install agent-inbox        # or
pip install agent-inbox         # into the current environment

Or run the MCP server as a container — see Hosting:

docker run -p 8080:8080 -v agent-mail-data:/data \
  salimfadhley/agent-inbox:latest

Quickstart (CLI)

Zero infrastructure: install the package, set your two-part identity — project + agent (--project / AGENT_MAIL_PROJECT and --from / AGENT_ID) — and run. The SQLite file is created on first use.

export AGENT_MAIL_PROJECT=agent-mail
export AGENT_ID=claude-opus

# direct: a specific agent on a project
agent-mail send --to agent-mail/codex --subject "corpus stale?" --body "reindex?"
# any one agent on a project (a shared work queue)
agent-mail send --to agent-mail --subject "task" --body "who can take this?"
# broadcast: every agent on a project
agent-mail send --to agent-mail/* --subject "heads up" --body "deploying in 5"

# read your own inbox (as agent-mail/codex)
AGENT_ID=codex agent-mail inbox
AGENT_ID=codex agent-mail read <id>
AGENT_ID=codex agent-mail reply <id> --body "on it"   # replies directly to the sender

Add --json to any command for machine-readable output.

Addressing: project/agent (direct) · project (any one agent) · project/* (broadcast).

Verb	What it does
send --to <target> --subject --body [--thread] [--intent]	Send to project/agent, project (any), or project/* (all)
inbox	List my unread messages (peek — does not ack)
read <id>	Show a message and ack it (consume)
reply <id> --body	Reply directly to the sender and ack the original
notify --to <target> [--thread]	Validate the address (best-effort; a no-op — SQLite can't wake a process)
ping	Round-trip a message to yourself to check the system is operational
doctor	Validate config + storage; print the db path, storage: ✅ ready, and the effective (redacted) config
hub-info	Show this hub's public self-description (name, connect URL, admin/feedback)
mcp-serve	Run the MCP server (see below)

# verify agent-mail is working end-to-end (send + inbox + read to yourself)
AGENT_MAIL_PROJECT=agent-mail AGENT_ID=claude-opus agent-mail ping

MCP server

The same verbs are exposed as MCP tools (send_message, check_inbox, read_message, reply_message, notify_agent, and ping — a self round-trip a client can call on sign-on to confirm everything works). Two ways to run it:

Local, per-agent (stdio). The client spawns it; identity is AGENT_MAIL_PROJECT + AGENT_ID.

AGENT_MAIL_PROJECT=agent-mail AGENT_ID=claude-opus agent-mail mcp-serve

Hosted, multi-agent (http). One server serves everyone. Each agent connects on its own address — the URL is its identity, /<project>/<agent>/mcp:

http://mail-host:8080/agent-mail/claude-opus/mcp   → agent-mail / claude-opus
http://mail-host:8080/goldberg/casework/mcp        → goldberg / casework

agent-mail mcp-serve --transport http --host 0.0.0.0

That personalized URL is an agent's entire configuration — no env, no headers. (?project=&agent= and X-Agent-Project + X-Agent-Id headers also work for programmatic clients.) See docs/mcp-clients.md to wire it into Claude Code, Codex, and others, and docs/hosting.md to deploy it.

The "check your inbox" convention

An agent only benefits from mail if it looks. Paste the ready-made block from docs/inbox-check-snippet.md into your agents' CLAUDE.md / AGENTS.md, and hand a new agent docs/agent-onboarding.md to get it participating.

Configuration

Settings resolve from four layers, later winning: field defaults → the baked defaults.toml → a runtime --config file.toml → environment variables. Every setting has one name usable as a lowercase TOML key or its UPPERCASE env var (db == AGENT_MAIL_DB). Containers set env vars; developers point at a TOML file:

agent-mail --config ./agent-mail.toml mcp-serve   # env still overrides the file
agent-mail doctor                                 # show effective config + check storage

Common settings: AGENT_MAIL_DB (the SQLite file path), AGENT_MAIL_TTL_DAYS (auto-purge age, default 14; 0 disables), AGENT_MAIL_MAX_MESSAGE_BYTES (default 1048576 = 1 MiB), AGENT_MAIL_PROJECT, AGENT_ID, AGENT_MAIL_TRANSPORT/HOST/PORT/PATH, AGENT_MAIL_HUB, and the hub's admin/feedback fields advertised via hub_info. Full reference: docs/configuration.md.

Development

uv sync --dev
uv run pytest                       # unit tests
uv run ruff check . && uv run ruff format --check .
uv run pyright

The test suite needs no external services — it runs against SQLite in normal CI.

See CONTRIBUTING.md for the coding standards and quality gates.

License

GPL-3.0-or-later.