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io.github.Postcept/mcp

Official registry Security

Verify agent actions against the system of record and get signed completion receipts.

Source code Documentation

Install

Add this to your client's MCP configuration (Claude Desktop: claude_desktop_config.json; Cursor: .cursor/mcp.json; VS Code and others use the same "mcpServers" shape).

NPM package @postcept/mcp
Claude Code 
claude mcp add io-github-postcept-mcp -e 'POSTCEPT_API_KEY=<your postcept_api_key>' -- npx -y @postcept/mcp@0.3.3
JSON configuration (Claude Desktop, Cursor, VS Code) 
{
    "mcpServers": {
        "io-github-postcept-mcp": {
            "command": "npx",
            "args": [
                "-y",
                "@postcept/mcp@0.3.3"
            ],
            "env": {
                "POSTCEPT_API_KEY": "<your postcept_api_key>"
            }
        }
    }
}

Environment variables

  • POSTCEPT_API_KEY required secret Postcept API key

Documentation

From the project's README on GitHub, refreshed weekly. Links open on GitHub.

Contents
  1. @postcept/mcp
  2. Configuration
  3. Use with Claude Desktop / Claude Code
  4. Tools
  5. Advisory, by design
  6. Development

@postcept/mcp

A Model Context Protocol server that exposes Postcept, outcome verification 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

VariableRequiredDefaultNotes
POSTCEPT_API_KEYyesnoneA Postcept API key (pcpt_sk_...) with verifications:write.
POSTCEPT_BASE_URLnohttps://api.postcept.comPoint 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

ToolPurpose
verify_refundVerify a claimed refund (exists, amount/currency/customer match, not duplicated).
verify_cancellationVerify a subscription was actually cancelled.
verify_ticketVerify a support ticket is in the expected state.
get_verificationFetch a past verification and its signed receipt by id.
reconcile_verificationRe-verify a past verification against the live system of record.
verified_completion_rateRead 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.

Advisory, by design

MCP puts the verification call in the agent's hands, which makes it the right integration for development, demos, and workflows where the agent's judgment is already trusted. It is advisory: an agent can skip the call, pass the wrong identifiers, or ignore the answer.

For consequential actions, enforce the decision outside the agent. The workflow or orchestrator calls the Postcept API (or the SDK's guard()) itself and branches on safe_to_claim_complete before anything customer-facing happens. The agent then receives the allowed outcome instead of deciding it. Both patterns use the same API and the same receipts, what changes is who owns the branch.

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

Frequently asked questions

What is io.github.Postcept/mcp?

Verify agent actions against the system of record and get signed completion receipts.

How do I install io.github.Postcept/mcp?

It runs on your machine. In Claude Code: claude mcp add io-github-postcept-mcp -e 'POSTCEPT_API_KEY=<your postcept_api_key>' -- npx -y @postcept/mcp@0.3.3. For other clients, paste the JSON configuration from this page into their MCP settings.

Does io.github.Postcept/mcp need an API key?

Yes. It expects POSTCEPT_API_KEY, which you set in its configuration.

Is io.github.Postcept/mcp open source?

Yes. Its code is on GitHub under the MIT license.

Who maintains io.github.Postcept/mcp?

It is published by Postcept. AI.tn lists it but does not maintain or endorse it.

From the official MCP Registry. Listing is not an endorsement: review a server's code and permissions before giving it access to your data.