gnt MCP Server

Run the setup below once and every agent your team runs has a git-native rulebook it has to check over MCP before it acts, approved the same way your code already is: a merged pull request.

• Rules live in your repo as files and ship through normal PRs, not a dashboard click.

• Agents call check_action over MCP before anything risky (a refund, a delete, a message to a customer) and get back an allow/block/escalate verdict.

• Every rule traces back to the git file and the PR that approved it, so "why did the agent do that" always has a paper trail.

Prefer not to run any of this yourself? The hosted version at gntai.dev does the same thing without you standing up a Postgres instance.

gnt prebrain scanning a repo, opening a PR, and getting it merged. A real terminal session, not a mockup.

Get started (30 seconds)

npm install -g @gnt-ai/cli
gnt login
gnt connect github
gnt prebrain
# merge the opened PR on GitHub. that merge is the approval

That merge lands a rule file in your connected repo, shaped like this:

your-repo/
└── rules/
    ├── refund-approval-threshold.md
    └── contract-legal-cc.md

Each file is plain markdown with YAML frontmatter:

---
title: Never refund over $500 without a manager
status: approved
confidence: 0.91
owner_id: finance-team
source_citations: [...]
source: slack
tags: [refunds, finance]
last_validated_at: 2026-07-20
version: 1
superseded_by: null
approved_by: jane@company.com
approved_at: 2026-07-21T14:03:00Z
created_at: 2026-07-18T09:12:00Z
pr_number: 142
pr_url: https://github.com/your-org/your-repo/pull/142
---

Refunds over $500 need manager sign-off before they go out...

Related MCP server: PolicyGuard

See it in action

There's no captured transcript to show yet (see the gap noted at the bottom of this README). Here's the actual response shape a check_action call returns, straight from the tool's contract:

{
  "verdict": "blocked",
  "reason": "Refund exceeds the $500 threshold without manager sign-off (rules/refund-approval-threshold.md)",
  "cited_rules": [
    { "id": "refund-approval-threshold", "title": "Never refund over $500 without a manager" }
  ],
  "rules_retrieved": 3
}

verdict is one of allowed, blocked, or needs_human. needs_human is the fail-closed default: no approved rule covers the action, retrieval failed, or the check couldn't complete. It never guesses.

What it does

One MCP endpoint, five tools:

Prerequisites

Install

gnt needs Node >=22.13. If the CLI fails to start with a version error, update Node first and confirm with node --version.

Common commands

gnt login                # sign in, store an API key locally
gnt connect github       # connect the repo your rules PRs open against
gnt prebrain             # scan sources, extract candidate rules, open PRs
gnt review               # review rules awaiting approval
gnt status               # show brain status
gnt pull                 # download the latest skill pack
gnt gaps                 # list uncovered queries with no approved rule

Config

Privacy

• No analytics or telemetry dependency in the CLI or the web app.

• gnt prebrain's default extraction mode is cloud, not on-device: your source text goes straight to Anthropic's API (or Vercel AI Gateway with zero-data-retention, if you configure it), never to gnt's own servers. Fully on-device extraction needs --mode local against a local Ollama daemon.

• The extracted rule candidates still get sent to gnt's API to open the PR. Raw source text stays off gnt's servers in cloud mode; the resulting rule text doesn't.

• Rules live in your connected GitHub repo and in gnt's own database. The MCP tools read from gnt's store, not by cloning your repo on every call.

• Self-hosting: apps/api only sends error data to Sentry if you set SENTRY_DSN yourself. Leave it unset and nothing goes out.

Team setup

• Who writes rules: anyone with access to your connected repo, either through gnt prebrain (batch-extracted from real sources) or gnt review (hand-proposed).

• How approval works: merging the PR is the approval. There's no separate publish step.

• What gets committed: rules/<rule-id>.md files with the frontmatter shown above and a plain markdown body.

Troubleshooting

Self-hosting: gnt login's browser step needs apps/web running. The base self-host compose stack doesn't start it by default. Run apps/web separately (its own pnpm dev or build) so /cli-login has somewhere to land, then retry gnt login.

ValueError: refusing to start: these settings still have their .env.example placeholder value... A change-me-... string is still sitting in apps/api/.env. The error names every offending field; generate a real value for each and retry.

store fails to start with GNT_STORE_INTERNAL_API_SECRET is not set. apps/store/.env wasn't filled in, or wasn't picked up. Confirm the file exists at that exact path, not still named .env.example.

Every store-to-api call gets rejected with 401 or 403, even though both services are up. STORE_INTERNAL_API_SECRET / APPROVAL_SIGNING_SECRET in apps/api/.env don't byte-for-byte match GNT_STORE_INTERNAL_API_SECRET / GNT_APPROVAL_SIGNING_SECRET in apps/store/.env. This fails closed by design. Regenerate both pairs so the two files agree.

A rule fails to save with an embedding or rerank error. apps/store/.env is missing ZEROENTROPY_API_KEY, or it's still empty. Get a real one from zeroentropy.dev.

Full command reference

gnt login
gnt logout
gnt connect <app>        github, slack, notion-mcp, monday-mcp, linear-mcp, jira-mcp,
                          sentry-mcp, granola-mcp, zoom-mcp, figma, datadog,
                          gitlab-threads, hubspot, airtable, openclaw, hermes
gnt disconnect <app>
gnt status
gnt billing
gnt review
gnt pull
gnt gaps
gnt prebrain              scan local sources, extract candidate rules, open batched draft
                           PRs (~60 flags for source paths and extraction mode, see
                           `gnt prebrain --help`; --mode cloud|local, cloud is the default)
gnt stale
gnt keys list|create|revoke|rotate
gnt webhook list|create|revoke
gnt org show|rename|invite|remove

Learn more

• Self-hosting walkthrough: docs/self-hosting/README.md

• Production hardening after self-hosting: apps/api/DEPLOY.md

• Security policy: SECURITY.md

License

Copyright © 2026 gnt.ai. Licensed under FSL-1.1-Apache-2.0, source-available today. See LICENSE for the terms and NOTICE for the trademark rule on forks: two years after this repo went public it converts to Apache-2.0 in full.

Contributing

See CONTRIBUTING.md for dev setup and how to open a PR. Every commit needs a Signed-off-by trailer (git commit -s), the Developer Certificate of Origin instead of a CLA. No separate form, just the flag.