Trail MCP Server

usetrail

The MCP server for Trail - it gives your coding agent your team's tracker and the project's durable memory, scoped to the folder you have open.

Your agent stops working blind. It reads what is open, writes what it did, and records what it learned the hard way - in the same board your team looks at, not in a scratch file that only that session can see.

This package is the client. It talks to your Trail account over the REST API; there is no database here. Dependencies are @modelcontextprotocol/sdk, zod and the built-in fetch.

Quick start

# 1. connect this machine to your Trail account (opens your browser; no token to copy)
npx -y usetrail@latest login

# 2. register it with your agent - this example is Claude Code
claude mcp add trail -s user -- npx -y usetrail@latest

No account yet? Create one at usetrail.dev - the free plan covers one project and three people.

Not tied to one agent. This is a plain MCP server over stdio, speaking the three protocol versions in use today. Any MCP-compatible client can run it; only the registration command differs, and each client documents its own.

Prefer a local checkout? Clone it instead, and the connector keeps itself up to date on its own (see Updating):

git clone https://github.com/arsprengel/trail-mcp.git ~/.trail-mcp
npm --prefix ~/.trail-mcp install --omit=dev
node ~/.trail-mcp/bin.js login
claude mcp add trail -s user -- node ~/.trail-mcp/bin.js

On Windows, write the real path instead of ~: the registration stores the argument verbatim and Node does not expand it.

What your agent gets

The tracker - list_items, get_item, add_item, update_item, move_item, get_next, delete_item. Real items on your team's board, with type, status, priority, assignees and history. Work the agent picks up shows as in progress and closes when it is done, so the board is not a story someone has to retell.

Project memory - list_memory, get_memory, add_memory, update_memory, review_memory. The durable knowledge of a project: the deploy that has a trap in it, the decision nobody should relitigate, the command that is not in any README. Shared by everyone on the project, human or agent. A new session reads it before acting instead of rediscovering it.

Reminders - add_reminder, list_reminders. Things with a date that must not be silently missed.

Attachments - add_attachment, get_attachment. Files that belong to an item.

Which project it writes to

Trail holds many projects. The connector uses the folder you have open as the project - the folder name, or whatever a .trail file next to it says, or the TRAIL_PROJECT variable. So the agent writes to the right project without being told, and two repositories never bleed into each other. To reach across, the agent passes project explicitly on the tool.

Session hook (Claude Code)

npx -y usetrail@latest hooks install

Registers an opening hook in ~/.claude/settings.json (with a backup, and without duplicating): every session that starts in a project with a tracker gets the open items and the project memory in context from the first message - the agent starts knowing, instead of depending on someone remembering to ask. Fail-silent by design: no login or no network and the hook stays quiet. hooks uninstall reverses it.

Clients without a hook mechanism are covered too: the server's own instructions tell the agent to fetch the summary itself before acting.

Your own Trail

Point it at your server once and it stays pointed:

TRAIL_API_URL=https://your-trail npx -y usetrail@latest login

Without that variable, login goes to the hosted service.

Commands

npx -y usetrail@latest            # start the MCP server over stdio - what your agent runs
npx -y usetrail@latest login      # connect this machine (browser confirmation, no token copying)
npx -y usetrail@latest status     # server address, current project, whether a token is present
npx -y usetrail@latest logout     # delete the saved token
npx -y usetrail@latest doctor     # find the install on this machine and unstick auto-updates

The token is stored at ~/.config/trail/token.json (mode 600). Revoke it whenever you want from the "AI token" panel in the app.

Configuration

The former names (TETHER_*) keep working, with no deadline - the product used to be called Tether, and nothing anyone already configured has to change.

Updating

The @latest is not decoration. Registered as npx -y usetrail@latest, the connector resolves the published version every time your agent starts a session, so a new release reaches you without anyone doing anything. Registered as bare npx usetrail, npm reuses whatever copy it cached the first time - and that machine stays on that version forever. Use @latest.

The cost of @latest is about a second at session start, and a network call. Neither matters in practice: the connector talks to Trail over the network anyway.

A cloned install updates itself differently: on startup it fires a quiet fast-forward pull in the background, at most every six hours. The running session keeps the version it loaded; the next one starts updated. No network or a local conflict and nothing happens, silently.

Stuck on an old version? npx -y usetrail@latest doctor finds the install, reports the version and unsticks it.

Requirements

Node 18 or newer.