MCP server Writ

writ-mcp

The Writ gate as an MCP server. Give any MCP-compatible agent point-of-action control: the agent calls Writ before a consequential write, gets back ALLOW, DENY, or STEP_UP, and every outcome creates an audit receipt.

Install

pip install writ-mcp

Requires Python 3.9+. Installs the writ-mcp command (stdio transport).

Configure

export WRIT_API_KEY="writ_..."        # required; get one free: POST /v1/keys with an email
export WRIT_SPONSOR_TOKEN="..."       # only for sponsor tools (grant, revoke, reinstate)
# export WRIT_BASE_URL="..."          # default: https://api.withwrit.com

Add to your agent

Claude Code:

claude mcp add writ --env WRIT_API_KEY="$WRIT_API_KEY" -- writ-mcp

Claude Desktop (claude_desktop_config.json):

{
  "mcpServers": {
    "writ": {
      "command": "writ-mcp",
      "env": { "WRIT_API_KEY": "writ_..." }
    }
  }
}

Any MCP client (generic stdio config):

{
  "command": "writ-mcp",
  "env": {
    "WRIT_API_KEY": "writ_...",
    "WRIT_SPONSOR_TOKEN": "writ_sp_..."
  }
}

Hermes (NousResearch/hermes-agent) catalog entry — once published, this package is installable from the optional-mcps catalog:

hermes mcp install writ

The check-before-write loop

The tool descriptions teach the agent this flow, but the short version:

1. writ_check(sponsor_id, agent_id, verb, target, purpose) — before the write.
2. ALLOW → you get a 90-second authToken bound to that exact write.
3. writ_verify_token(auth_token, verb, target, purpose) — immediately before executing, to prove the authorization still matches what you're doing.
4. DENY → do not proceed. STEP_UP → a human sponsor approves (via writ_grant or the dashboard), then check again.
5. writ_lease(auth_token, system_id, method, path, body) - convert the ALLOW token into a single-use lease bound to the exact upstream request.
6. writ_execute(lease_id, method, path, body) - run the gated write with the same method/path/body; the gate forwards it with the vaulted credential and returns the upstream response verbatim.

Tools

Tool	Who	What
writ_check	agent	Decision + 90s purpose-bound token
writ_verify_token	agent	Point-of-action token verification
writ_lease	agent	Convert an ALLOW token into a single-use gated-execution lease
writ_execute	agent	Run one gated upstream request with a lease or ALLOW token
writ_grant	sponsor	Approve a STEP_UP (one-time grant)
writ_revoke / writ_reinstate	sponsor	Kill switch on/off for a principal
writ_receipts	agent	Audit trail of decisions
writ_policy	agent	Tenant verb policy
writ_sandbox	anyone	Free 90-second demo grant, no key needed
writ_github_installations	admin	List connected GitHub App installations
writ_github_set_threshold	admin	Set the check-run fail threshold per install
writ_github_toggle_pr_comments	admin	Enable/disable the PR-comment bot
writ_manifests	agent	List repos with risk profiles or fetch one manifest
writ_explain_receipt	agent	Explain a receipt in plain language
writ_tenant_notify	admin	Get or update step-up notification settings
writ_principals	admin	List the tenant's principals
writ_verbs	admin	List the tenant's verb vocabulary
writ_keys	admin	List API key metadata

Try it with no key: writ_sandbox → writ_check with verb="demo_write".

Source

Public repo: withwrit/pywrit (mcp/ directory). License: MIT.

Directory listings: Glama · MCP Registry io.github.withwrit/writ.