@postcept/mcp

@postcept/mcp

A Model Context Protocol server that exposes Postcept: Proof-of-Completion for AI agents as MCP tools.

After an agent performs a high-risk action (a refund, a subscription cancellation, a support-ticket resolution), it calls a verify_* tool to confirm the action actually completed in the system of record (Stripe, Zendesk, and more) and obtain a signed completion receipt. "done" becomes proof, not a claim.

The server is a thin wrapper over the live Postcept HTTP API. It holds no credentials of its own beyond your Postcept API key, and verification is read-only against your systems of record.

Configuration

Variable	Required	Default	Notes
POSTCEPT_API_KEY	yes	none	A Postcept API key (pcpt_sk_...) with verifications:write.
POSTCEPT_BASE_URL	no	https://api.postcept.com	Point at a self-hosted or staging API.

Create an API key in the Postcept dashboard under API keys.

Use with Claude Desktop / Claude Code

{
  "mcpServers": {
    "postcept": {
      "command": "npx",
      "args": ["-y", "@postcept/mcp"],
      "env": { "POSTCEPT_API_KEY": "pcpt_sk_..." }
    }
  }
}

Tools

Tool	Purpose
verify_refund	Verify a claimed refund (exists, amount/currency/customer match, not duplicated).
verify_cancellation	Verify a subscription was actually cancelled.
verify_ticket	Verify a support ticket is in the expected state.
get_verification	Fetch a past verification and its signed receipt by id.
reconcile_verification	Re-verify a past verification against the live system of record.
verified_completion_rate	Read the organization's Verified Completion Rate.

Every verify_* tool accepts test: true to run against the deterministic sandbox connector (excluded from your Verified Completion Rate), so an agent can exercise the full flow without a live system of record.

A non-verified result (incomplete, duplicated, mismatched, policy_failed) means the work is not done. Surface the gap and recover.

Development

pnpm --filter @postcept/mcp build       # compile to dist/
pnpm --filter @postcept/mcp typecheck
POSTCEPT_API_KEY=pcpt_sk_... node dist/index.js   # stdio server