Agent Mandate Verification MCP server

Verify a signed agent mandate through MCP

Check a signed authorization envelope before trusting an agent's claimed authority.

Agent Mandate's MCP tool accepts the complete { mandate, signature } envelope returned by POST /v1/mandates. Raw claims are not a signed envelope.

The walkthrough: create an envelope, verify an action through MCP, then change one signed field and verify again. You see the real verification result for each request, including the one that gets refused.

Requirements: Node.js 20 or newer, and an Agent Mandate API key.

Getting a key: the free tier includes 500 verified actions per month and needs no card. Issuing mandates is free and never consumes the allowance; one unit is one action verified. Paid plans start at $299/month for 10,000 verified actions. This walkthrough consumes at most two of your free units.

Running this in production? When a signed mandate is and is not worth it, with the published pricing. Short version: if the approval gate is one you control, a policy check inside your own service is simpler and cheaper. The signature earns its price when somebody other than you has to be able to verify the decision.

Just exploring? POST /v1/demo/verify takes raw claims, needs no key at all, and is shown at the end. It does not replace the signed-envelope walkthrough, because it does not check a signature.

Run the walkthrough

git clone https://github.com/API-Disk-Integrations/agent-mandate-mcp.git
cd agent-mandate-mcp
git checkout v0.1.1
npm ci
AGENT_MANDATE_API_KEY=your_key node examples/verify-mandate.mjs

The example runner comes from this repository, but it installs @api-disk-integrations/agent-mandate-mcp@0.1.1 from npm into a throwaway prefix and runs that, so it exercises the published artifact rather than your working tree. Omit AGENTMANDATEAPI_KEY and it prompts without echoing.

What it prints

=== 1. Create a mandate ===
POST /v1/mandates -> 200
envelope keys: mandate, signature, requestId
signature: v1:b63eacaa7… (67 chars)

=== 3. Verify the action against the signed envelope ===
action: payments.transfer 30000 USD, approval required above 25000
decision: requires_approval
  violation: Actions above 25000 minor units need a human approval token.
  digest: c90fd0bc104dce63…

=== 4. Tamper with one signed field, keep the signature ===
raising approvalRequiredAboveMinor 25000 -> 999999, which would turn this into an allow
rejected: Agent Mandate error 400/invalid_request.
The tampered mandate did not buy an allow. The signature is doing its job.

That is a real run against production, not illustrative output. The grant allows up to 100,000 minor units but requires approval above 25,000, and the action asks for 30,000, so requiresapproval is the correct answer. A deny or requiresapproval is a correct result, not a failure.

Verification reports a result; your application remains responsible for enforcing it.

Install the server

npx --yes @api-disk-integrations/agent-mandate-mcp@0.1.1

A generic stdio client configuration:

{
  "mcpServers": {
    "agent-mandate": {
      "command": "npx",
      "args": ["--yes", "@api-disk-integrations/agent-mandate-mcp@0.1.1"],
      "env": {
        "AGENT_MANDATE_API_KEY": "${AGENT_MANDATE_API_KEY}"
      }
    }
  }
}

${AGENTMANDATEAPI_KEY} denotes the host's secret reference; use your client's documented secret facility if its syntax differs. The package uses stdio and reads exactly that environment variable. It has no remote /mcp endpoint.

Pin the version. 0.1.0 is still on the registry and has a first-use defect: its input schema accepted any object for mandate, so a call built from the keyless demo's shape returned HTTP 400.

Shortened. The full README is on GitHub.