MCP Server

The @peac/mcp-server package exposes PEAC Protocol as MCP tools. AI agents can verify receipts, inspect claims, decode tokens, issue new receipts, and create evidence bundles -- all through the standard Model Context Protocol interface.

226 tests across 22 test files

The MCP server is extensively tested. Every tool handler, error path, and security boundary has coverage.

Install

Terminal

npm install @peac/mcp-server

Quick start

Terminal

npx peac-mcp-server

The server starts on stdio transport by default, ready for any MCP client.

---

Tools

The MCP server exposes 5 tools in two security tiers.

Pure tools

Available immediately, no secrets required.

Tool	Input	Output
peac_verify	Receipt JWS + issuer URL	Verification result with 12 checks
peac_inspect	Receipt JWS	Decoded header, payload, metadata
peac_decode	Raw JWS string	Base64url-decoded parts

Privileged tools

Disabled by default. Require explicit capability configuration.

Tool	Input	Output
peac_issue	Claims + signing config	Signed receipt JWS
peac_create_bundle	Receipt array + issuer	Evidence bundle file

Privileged tools require opt-in

Set PEAC_MCP_PRIVILEGED=true and provide signing keys to enable peac_issue and peac_create_bundle.

---

Usage examples

Verify a receipt

Tool call

{
  "tool": "peac_verify",
  "arguments": {
    "receipt": "eyJhbGciOiJFZERTQSIs...",
    "issuer_url": "https://api.example.com"
  }
}

Response

{
  "verified": true,
  "checks": [
    { "id": 1, "name": "signature_valid", "passed": true },
    { "id": 2, "name": "algorithm_allowed", "passed": true },
    { "id": 3, "name": "type_header_present", "passed": true }
  ],
  "claims": {
    "iss": "https://api.example.com",
    "sub": "agent:claude-123",
    "peac": { "type": "api.request", "status": "executed" }
  },
  "_meta": {
    "serverVersion": "0.10.13",
    "policyHash": "sha256:abc...",
    "protocolVersion": "peac-receipt/0.1"
  }
}

Inspect a receipt

Tool call

{
  "tool": "peac_inspect",
  "arguments": {
    "receipt": "eyJhbGciOiJFZERTQSIs..."
  }
}

Returns the decoded header (alg, typ, kid), payload (all claims), and signature metadata without performing verification.

Issue a receipt

Tool call (privileged)

{
  "tool": "peac_issue",
  "arguments": {
    "issuer": "https://api.example.com",
    "subject": "agent:claude-123",
    "type": "tool.call",
    "attestation_type": "interaction",
    "status": "executed"
  }
}

Returns a signed JWS string ready for delivery.

---

Configuration

Environment variables

Environment

# Enable privileged tools
PEAC_MCP_PRIVILEGED=true

# Signing key for peac_issue
PEAC_PRIVATE_KEY=<base64url-ed25519-private-key>
PEAC_KID=peac-2026-02

# Optional: policy file path
PEAC_POLICY_PATH=/path/to/policy.json

Policy file

Fine-grained capability control:

policy.json

{
  "capabilities": {
    "verify": true,
    "inspect": true,
    "decode": true,
    "issue": false,
    "bundle": false
  },
  "issuer": {
    "url": "https://api.example.com",
    "kid": "peac-2026-02"
  }
}

---

Structured outputs

Every tool response includes _meta for traceability and auditability:

{
  "_meta": {
    "serverVersion": "0.10.13",
    "policyHash": "sha256:<canonical-hash-of-loaded-policy>",
    "protocolVersion": "peac-receipt/0.1"
  }
}

The policyHash is deterministic -- same policy always produces the same hash.

---

Security model

The MCP server is designed with defense-in-depth:

Measure	Description
No ambient key discovery	Keys must be explicitly configured via env vars
Static policy	Policy loaded at startup, never fetched at runtime
SSRF prevention	No outbound network requests from tool handlers
Buffer growth cap	Bounded memory allocation for all inputs
Capability-based access	Privileged tools require explicit opt-in
Handler-transport separation	Core logic is transport-neutral, tested independently

---

Integration with Claude Desktop

Add to your claude_desktop_config.json:

claude_desktop_config.json

{
  "mcpServers": {
    "peac": {
      "command": "npx",
      "args": ["peac-mcp-server"],
      "env": {
        "PEAC_MCP_PRIVILEGED": "false"
      }
    }
  }
}

Once configured, Claude can verify any PEAC receipt you paste into the conversation.

---

Next steps

Agent protocols

How PEAC maps to MCP, ACP, A2A, and other agent communication protocols.

OpenClaw capture

Capture interaction evidence with the OpenClaw adapter pipeline.