mail-index

mail-index

mail-index downloads a preview of your whole inbox to your machine, then smartly fetches the full text of the messages that matter as you use it. That local index lets your AI agent run true summarization and recall over your entire mailbox — instead of being trapped behind Gmail's search bar.

It works through a local MCP server, so any agent (Claude, Codex, any MCP client) can query it. Local-first — the default index never leaves your machine. Operators who need an always-on connector can instead deploy the optional, single-tenant remote Worker Deployment in their own Cloudflare account; mail-index operates no hosting service. Read-only by default — it never mutates your mail unless you explicitly opt into archive + label edits (a gmail.modify re-auth) or, on the remote Deployment, drafts (a gmail.compose re-auth). It never sends or deletes mail. Both opt-in scopes can send at the token level, so that guarantee is enforced in code (a send guard on the Gmail runner plus test/drafts.test.ts), not by the scope. See ADR-0007 and ADR-0011.

Ask a vague question → one local MCP call → ranked, snippet-first answer. Interactive version →

Status: v1.5 — published. Progressive sync, the correspondence graph, the

interest engine, curation, the full MCP surface, and the write-back

loops are built and tested — and mail-index is live on

[npm](https://www.npmjs.com/package/mail-index) with a

[`.mcpb` bundle](https://github.com/unsoldgroup/mail-index/releases/latest).

Still in progress: the bundled Option A OAuth client and signed one-click

installers. Architecture lives in

[docs/PLAN.md](docs/PLAN.md); start with [docs/INSTALL.md](docs/INSTALL.md);

every release is recorded in [CHANGELOG.md](CHANGELOG.md).

[!TIP]

New in v1.5 — the optional remote Deployment. mail-index can now also run

as a single-tenant Cloudflare Worker in your own account: always-on, synced

on a cron, and reachable by remote agents over authenticated MCP (plus a small

A2A surface). It serves the _same_ tool registry as the local server, backed by

a D1 storage driver that passes the same FTS ranking conformance suite, and

it can push — Trigger rules match new mail as it lands and fire signed

webhooks. Long O(N) work becomes a queued Job instead of a command

handback. You can seed a fresh Deployment straight from your existing local

index with mail-index export → D1 import, so it starts with your history

already indexed. **The local CLI + stdio path is unchanged and stays the

default**, and mail-index still operates no hosting service — the Worker is

code you deploy to infrastructure you own.

See [docs/INSTALL-worker.md](docs/INSTALL-worker.md),

[docs/WORKER-SEED.md](docs/WORKER-SEED.md),

[ADR-0008](docs/adr/0008-self-hosted-remote-deployment.md).

Also new locally: every MCP response carries a freshness block and any

stale read now auto-triggers a background sync (previously only the digest

composites did).

[!TIP]

From v1.4 — opt-in mailbox writes + human-readable labels.

mail-index can archive a message and edit its labels directly on

Gmail — via the archive / label CLI commands and the archive_message /

modify_labels MCP tools, on both the gog and gws adapters. It stays

read-only by default: writes are unreachable until you opt in with a

gmail.modify grant (mail-index never sends or deletes; the scope could

send, so a code guard enforces this, see ADR-0011) — enable per

account with mail-index setup --account --enable-writes or the

bundled scripts/enable-writes.sh. Labels render as their human names

everywhere (the index caches Gmail's label catalogue and resolves

Label_3546… → _"Expedition Insure"_ in both directions), and you can pass a

friendly label name to label --add/--remove.

See [ADR-0007](docs/adr/0007-opt-in-mailbox-writes.md).

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How it works

1. Progressive sync — metadata for the whole mailbox in minutes; bodies fetched selectively.
2. Graph — contacts, domains, threads; centrality + communities over your _human_ (non-bulk) mail.
3. Interest — an engagement score per contact from read/reply/star/importance signals. A _seed for your curation_, not an autonomous decision.
4. Curate — you (via your agent, or a CLI wizard) confirm who/what matters; that profile drives which bodies get fetched.
5. Query — your agent searches, traverses the graph, and reads the messages that matter, all locally via MCP.

Important messages prewarm a local index; the MCP reads from it, touching Gmail again only when a needed body isn't there yet. Interactive version →

Quick start

Requires Node 24+ and a Gmail MailSource adapter — `gog` (recommended) or `gws`. Reading Gmail needs a Google OAuth client, and you get one two ways: use the mail-index beta client (skip Google Cloud entirely; request access to join the ~100-user test list) or bring your own Google Cloud client (no cap, no request — we walk you through it). See docs/INSTALL.md §2 and docs/oauth-and-verification.md.

npm install -g mail-index                    # or: pnpm add -g mail-index

mail-index init # scaffold the config

…connect a mailbox (own OAuth client, read-only) — see docs/INSTALL.md §2 / agent-install.md…

mail-index sync --account personal --since 6mo mail-index graph build --account personal mail-index search "that contract we discussed"

_(Prefer source? git clone …, pnpm install && pnpm build, then run the bins as node dist/cli/index.js ….)_

Add to Claude

The MCP server registers in one step, but it still needs a mailbox connected first (see the walkthrough). A .mcpb/claude mcp add only adds the server — it doesn't install the adapter, sign you in, or sync.

• Claude Code: claude mcp add --transport stdio mail-index -- npx -y -p mail-index mail-index-mcp (on Windows, prefix with cmd /c: … -- cmd /c npx -y -p mail-index mail-index-mcp — bare npx/.cmd won't spawn. See docs/INSTALL.md §7.)
• Any MCP client (manual):

  { "mcpServers": { "mail-index": { "command": "mail-index-mcp" } } }

• Claude Desktop: download the [`.mcpb` bundle](https://github.com/unsoldgroup/mail-index/releases/latest/download/mail-index.mcpb) and double-click it (unsigned during beta — you may need to allow it in System Settings / Windows SmartScreen). The bundle is self-contained (ships its own dependencies, run by Claude Desktop's bundled Node — no npx, network, or system Node needed) so it installs identically on Windows/macOS/Linux. A signed all-in-one installer that _also_ installs the adapter, signs you in, and syncs is still in progress; there is no claude:// install link.

Teach your agent the common moves. The MCP server already tells the agent _when_ to reach for it (purchases, receipts, bookings, "who said what", "catch me up"), and the repo ships a Claude [Agent Skill](skills/mail-index/SKILL.md) with the typical recipes (find purchases, catch up, find a contact's mail, summarize a sender). Drop it in for Claude Code/Desktop:

mkdir -p ~/.claude/skills && cp -R skills/mail-index ~/.claude/skills/

Full walkthrough (auth, curation, enrichment, scheduled sync, desktop-app gotchas) → [docs/INSTALL.md](docs/INSTALL.md). Driving setup with an agent → [docs/agent-install.md](docs/agent-install.md).

What to expect — time & storage

The index keeps metadata for every message and full text only where it earns it, so it grows with message _count_, not mailbox size — about 1.5% of your Gmail. First sync runs ~50 messages/min (one-time, incremental after); search is instant. Start with --since 1mo for value in minutes, then expand. Sizing table & growth path → [docs/INSTALL.md §9](docs/INSTALL.md#9-grow-your-index-intelligently).

Why it's lighter than Gmail search

Stock Gmail-API MCPs are query-based lookup tools — exact query, a network round-trip per call, raw payloads dumped into the model's context. mail-index answers _vague_ questions from a local recall index. Across a 100-question suite on a real mailbox it answered every question for 15× fewer tokens — and the gap widens exactly where a query-based MCP has no primitive at all: summarizing, relationships, and commitments.

Per-category tables, the read-one-message comparison, the tool-by-tool landscape, and how to reproduce it all → [docs/COMPARISON.md](docs/COMPARISON.md).

Stack

TypeScript · node:sqlite (no native deps) · SQLite FTS5 · Graphology · @modelcontextprotocol/sdk. Node 24+. Pluggable MailSource adapters; ships two Gmail transports — gog (recommended) and Google's gws.

CLI

Two bins ship: mail-index (CLI) and mail-index-mcp (the stdio MCP server).

mail-index init                          Scaffold the operator config + data dir

mail-index sync --account [--since 30d|1mo] [--all] [--query ] [--limit N] mail-index sync --all-accounts Sync every account by its policy presets mail-index enrich --account [--profile | --rule direct|all] [--sender ] [--match ] [--limit N] mail-index graph build [--account | --all-accounts] mail-index curate [--account ] Interactive curation wizard (no-agent fallback) mail-index compact [--account ] [--now] Demote summarized bulk bodies (ADR-0003) mail-index search [--account ] [--limit N] [--enrich] mail