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Issue signed receipts for AI agent actions; verify any receipt offline - free, no account (stdio).
About
Issue signed receipts for AI agent actions; verify any receipt offline - free, no account (stdio).
Security Report
PCRZERO MCP server is well-designed with strong security controls. Authentication is properly scoped (API key required only for paid operations), and the code demonstrates rigorous attention to credential handling through redaction and clean separation of concerns. Comprehensive security acceptance tests validate auth guarantees. Minor code quality observations around error handling breadth and input validation do not materially impact the strong security posture. Supply chain analysis found 1 known vulnerability in dependencies (0 critical, 1 high severity). Package verification found 1 issue.
7 files analyzed · 5 issues found
Security scores are indicators to help you make informed decisions, not guarantees. Always review permissions before connecting any MCP server.
Permissions Required
This plugin requests these system permissions. Most are normal for its category.
What You'll Need
Set these up before or after installing:
Environment variable: PCRZERO_API_KEY
How to Install
Add this to your MCP configuration file:
{
"mcpServers": {
"com-pcrzero-mcp": {
"env": {
"PCRZERO_API_KEY": "your-pcrzero-api-key-here"
},
"args": [
"-y",
"@scytalex-llc/pcrzero-mcp"
],
"command": "npx"
}
}
}Documentation
View on GitHubFrom the project's GitHub README.
PCRZERO — MCP server
Issue and verify signed receipts for agent actions from any MCP-speaking agent. PCRZERO adjudicates an attestation document against a policy and hands back a cryptographically signed receipt pair — durable, independently checkable proof that this decision was made, by these keys, over this document. Anyone can verify a receipt, offline, without an account and without trusting us.
- Website: pcrzero.com
- Sign up / API keys: pcrzero.com/signup
- API:
api.pcrzero.com
Install
Add the server to your MCP client. The package runs over stdio — your agent host launches it; nothing listens on a port.
Claude Code
claude mcp add pcrzero -e PCRZERO_API_KEY=<your-key> -- npx -y @scytalex-llc/pcrzero-mcp
Claude Desktop / any JSON-configured MCP client
{
"mcpServers": {
"PCRZERO": {
"command": "npx",
"args": ["-y", "@scytalex-llc/pcrzero-mcp"],
"env": { "PCRZERO_API_KEY": "<your-key>" }
}
}
}
No key yet? Leave env out. verify_receipt and get_keyset work with no API key
and no account — only the paid tool needs one.
Requires Node 22 or later.
The three tools
| Tool | Cost | What it does |
|---|---|---|
issue_receipt | Metered — bills one receipt_verifications unit per call | Adjudicates an attestation document against a policy on the live API and returns the verdict with a signed receipt pair. A fail verdict bills exactly like a pass: you are paying for the adjudication, not for the answer you wanted. The only tool here that spends. |
verify_receipt | Free, and it stays free | Checks a PCRZERO receipt pair against the signing keyset: whether the signature holds, and whether the receipt says what it appears to say. Offline by default — supply keyset and this call touches the network not at all; omit it and the server fetches the public keyset once. keyset_source in the result tells you which happened, every time. |
get_keyset | Free | Returns the current PCRZERO signing keyset — key ids, public halves, each key’s status. Public and unauthenticated. The same document an outside party fetches to check a receipt without trusting us. |
Current pricing is published at pcrzero.com — it is deliberately not baked into this README or into any tool description.
Auth, exactly
PCRZERO_API_KEY in the server’s environment, via your MCP client configuration. It is
sent as Authorization: Bearer on issue_receipt calls and used nowhere else: the key
never appears in tool results, error text, or logs — not even redacted. With no key
configured, issue_receipt refuses cleanly (auth_missing) and the two free tools keep
working.
API errors pass through verbatim (code, message, request_id). This server never
rewrites, retries, or softens a billing refusal.
Verify without trusting us
A PCRZERO receipt is checkable by anyone holding the public keyset — including people
who are not our customers and never will be. Call get_keyset once (or fetch
https://api.pcrzero.com/v1/keys yourself), pin it, and verify_receipt runs entirely
offline from then on. If we disappeared tomorrow, every receipt ever issued would still
verify.
Transport & scope
stdio only. No listen socket, no state, no receipt storage, no key-management tools — key management is a human path at pcrzero.com by design.
Proprietary — © Scytalex LLC. The receipt verification path is free to use for anyone, forever.
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