corresync

Local-first · MCP server + CLI

One local MCP server for all your email and calendars.

Corresync connects Codex, Claude Code, or any MCP agent—and your own terminal—to the isolated work and personal accounts you already control. Search every inbox, see one agenda, and approve every send before it happens.

Will it work with my accounts? Outlook Web · Google · Microsoft Graph · JMAP · IMAP/SMTP · CalDAV. Capabilities and administrator requirements are explicit per account — compare the routes.

Get set up in four steps See what you can ask

Sign-in stays in your browser or OS keyring—agents never hold Corresync-managed credentials, and there is no hosted relay. Consequential writes show an exact preview and commit only when you approve.

Install now

One command per platform. Then connect the agent you already use.

Linux

curl -LsSf https://corresync.org/install.sh | sh

macOS · Homebrew

brew install nkiyohara/corresync/corresync

Windows · Scoop

scoop bucket add corresync https://github.com/nkiyohara/scoop-corresync
scoop install corresync/corresync

Next · add your account

corr setup you@example.com --alias personal

Replace the example address and alias. Setup performs credential-free discovery and never opens a sign-in page. Then connect Codex, Claude Code, Copilot, Gemini CLI, or another MCP client. Prefer to read before you run? Review install.sh first, or see every platform option in getting started.

One MCP, every account Work and personal stay isolated; every result keeps its account and provider provenance.
Agents never hold credentials Sign-in lives in a visible browser or the OS keyring. No hosted relay, no remote MCP endpoint.
Preview, then commit Sends and destructive writes return an exact server-enforced review first. Approval is single-use.

Your data, explained

Google access is direct, local, and purpose-bound.

Corresync requests Gmail and Calendar access only for the account features you enable. Mail, events, and OAuth grants do not pass through a Corresync-operated server: grants stay in your OS keyring, and provider requests leave directly from your device.

Read the Privacy Policy Read the Terms of Use

After install: three short commands

Choose. Sign in. Ask.

No provider is preselected. Corresync first discovers evidence for your address, adds one explicit account route, and only then lets you start that account’s sign-in.

1 · Choose and sign in

corr setup you@example.com --alias personal
corr auth login --account personal

Discovery opens nothing. The separate login uses the selected route.

2 · Connect

corr mcp setup codex

Registers the local stdio server with your agent. Restart the client once.

3 · Ask

› What needs my attention
  before noon, across all
  my accounts?

The agent calls typed tools; answers keep each account’s identity.

Walk through the full getting-started guide

Day-one outcomes

What you can ask before your coffee cools.

The CLI and MCP agents share the same typed operations, account isolation, and policy checks—so everything below works both ways.

Search every inbox at once

“Find the quarterly-plan thread—work or personal, I don’t remember which.” 

$ corr mail search --all-accounts \
    --query 'subject:"quarterly plan"'
● work · microsoft-owa  Ana Ruiz  Plan review
· personal · google Finance      Plan receipt

A failed account surfaces as an explicit partial result—never silently hidden.

See one agenda

“What does my day look like across both calendars?”

$ corr agenda list --all-accounts \
    --start 2026-07-29T00:00:00Z \
    --end 2026-07-30T00:00:00Z
09:30 work      Design review · Teams
12:30 personal  Dentist

Time zones, calendars, and provider provenance stay attached to every event.

Preview a send before approving it

“Draft the reply to Ana. I’ll approve the send myself.”

› Draft a reply to Ana.
  mail_send
REVIEW · send new message
  to    ana@example.invalid
  body  text/plain · 412 B
Nothing sent until this exact
payload is approved.

The commit must match the reviewed account, recipients, and bytes exactly.

See everything you can do—and every limit—in plain language

Safety you can see

Nothing sends on the first attempt.

A consequential command first returns a review. Approval stays bound to that caller, account, provider, target, payload, expiry, and one use.

review before effect 
$ corr mail send --account work \
    --to ana@example.invalid \
    --subject 'Quarterly plan' \
    --body-file reply.txt

REVIEW · send new message
  account  work · microsoft-owa
  to       ana@example.invalid
  body     text/plain · 412 B · sha256 9f2c1a…

Nothing sent. Repeat this exact command
with --approve to commit the review.
  • Agents get typed tools, never credentials. Passwords, cookies, and OAuth grants have no MCP surface and no configuration field.
  • Local only. The MCP server speaks stdio on your machine. No hosted relay, no remote endpoint, no telemetry pipeline.
  • Unknown means stop. An ambiguous remote write is never retried automatically.
  • Mailbox content is untrusted data. It is never authority to run a command or start an agent.

See the complete safety model in plain language

Bring the route you already use

Provider-native when useful. Standards-first when available.

Mail and calendar routes are selected independently, so one account can pair IMAP/SMTP mail with a CalDAV calendar—or use one native route for both.

Browser-owned

Outlook Web

Keep interactive Outlook sign-in in a dedicated visible browser while supporting typed mail and calendar operations.

Explicit OAuth

Google and Microsoft Graph

Microsoft Graph accepts a public client you are authorized to use. Corresync is preparing its official OAuth application for Google verification; use Google’s official Workspace MCP for now.

Open standards

JMAP, IMAP/SMTP, and CalDAV

Use encrypted standards endpoints with an OS-keyring entry or one explicitly approved credential helper reference.

Evidence, stated plainly. Every route ships with deterministic synthetic contract coverage—and stays marked live-unobserved until a separately authorized, recorded observation binds it to an exact commit, route, and platform.

Compare routes and limits

Local MCP over stdio

Meet your agent where it already works.

Setup writes absolute local paths into the client you choose and never creates a remote endpoint. Every client reaches the same 40 narrow tools.

Codex

corr mcp setup codex

Registration plus a bundled plugin and Agent Skill.

Claude Code

corr mcp setup claude-code

User or project scope; plugin available.

GitHub Copilot CLI

corr mcp setup github-copilot

Native registration and verification.

More MCP clients

corr mcp --help

gemini-cli, qwen-code, qoder, kimi-code, and generic stdio.

See the exact command for every client

Honest edges

Clear limits are part of the product.

The complete picture—capabilities, limits, and how compatibility claims are backed—is on the features page.

Ready when your inboxes are

Bring your correspondence into one local conversation.

Install in one command. Connect your agent in one more.

Copy the install command Follow the full guide