Sign a contract as an agent. Requires a qc_agnt_* API key. Produces an Ed25519 signature over SHA-256(contentHash || timestamp || did). The signature is embedded in the contract\
AI agents use sign_as_agent to commit financial operations through QuickContract MCP — usually the final step of a payment, billing, or trading workflow. A call moves real money.
Signing a contract creates legally binding financial and legal obligations. This action is irreversible once executed and can commit the organization or agent to contractual terms, payments, or other obligations. It spans both Financial and Destructive categories, but Financial is most severe given the legal/financial commitments a signed contract entails.
From the tool's definition Sign a contract as an agent... The signature is embedded in the contract
Attacks that exploit this kind of access
Sign a contract as an agent. Requires a qc_agnt_* API key. Produces an Ed25519 signature over SHA-256(contentHash || timestamp || did). The signature is embedded in the contract\. It is categorised as a Financial tool in the QuickContract MCP MCP Server, which means it involves financial transactions. Block by default and require explicit approval.
Register the QuickContract MCP server in PolicyLayer and add a rule for sign_as_agent: allow, deny, rate-limit, or require approval. Point your MCP client at the PolicyLayer proxy URL and the rule is enforced on every call, before it reaches QuickContract MCP. Nothing to install.
sign_as_agent is a Financial tool with critical risk. Critical-risk tools should be blocked by default and only enabled with explicit human approval.
Yes. Add a rate_limit block to the sign_as_agent rule in your PolicyLayer policy. For example, setting max: 10 and window: 60 limits the tool to 10 calls per minute. Rate limits are tracked per agent session and reset automatically.
Set action: deny in the PolicyLayer policy for sign_as_agent. The AI agent will receive a policy violation error and cannot call the tool. You can also include a reason field to explain why the tool is blocked.
sign_as_agent is provided by the QuickContract MCP server (quickcontractio/mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Every MCP server has a record like this.
Type a name, get the same breakdown: verified identity, auth posture, risk grade, capabilities, recommended policy.
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