A2A Agent Card Validator & Extension Checker — OpenChainGraph compute node (compliance_control). Runs deterministically in-browser; zero PII, zero egress. Exports an AP2 artifact with execution_hash for chain provenance. Consumes upstream artifacts from: art-22-agentic-payments-protocol-comparato...
AI agents call verify_a2a_agent_card to retrieve information from Ainumbers Mcp Apps without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
| Parameter | Type | Required | Description |
|---|---|---|---|
compute | string | — | Compute mode (v0.4 Compute Binding). "auto" (default) = server for gpu:false nodes with registered kernels; "server" = force server-side; "browser" = always ret |
parent_hashes | array | — | execution_hash values from upstream ChainGraph AP2 artifacts to chain from (sets chain.parent_hashes in the export). |
parent_tool_ids | array | — | tool_id values matching parent_hashes, in the same order. |
policy_parameters | object | — | Input parameters for this tool's decision function. For gpu:false nodes with a registered kernel, these are computed server-side when compute is "auto" or "serv |
Parameters from the server's own tool schema.
This is a verification/validation tool that reads and checks card artifacts, extracts compliance information, and produces hashes for provenance tracking. There is no indication of data creation, modification, deletion, code execution, or financial transactions. The tool consumes upstream artifacts and exports structured data, which is characteristic of a Read operation.
From the tool's definition Tool performs validation and checking of A2A Agent Card artifacts ('Validator & Extension Checker') with outputs that are artifacts with execution hashes for 'chain provenance'.
Attacks that exploit this kind of access
A2A Agent Card Validator & Extension Checker — OpenChainGraph compute node (compliance_control). Runs deterministically in-browser; zero PII, zero egress. Exports an AP2 artifact with execution_hash for chain provenance. Consumes upstream artifacts from: art-22-agentic-payments-protocol-comparator. Output feeds: art-26-x402-payload-decoder-flow-simulator, art-18-mcp-developer-readiness-scorecard, ptg-01-ap2-prompt-template-generator. Open at: https://ainumbers.co/chaingraph/art-25-a2a-agent-card-validator.html. It is categorised as a Read tool in the Ainumbers Mcp Apps MCP Server, which means it retrieves data without modifying state.
verify_a2a_agent_card accepts 4 parameters: compute, parent_hashes, parent_tool_ids, policy_parameters. The full parameter table on this page comes from the server's own tool schema.
Register the Ainumbers Mcp Apps MCP server in PolicyLayer and add a rule for verify_a2a_agent_card: 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 Ainumbers Mcp Apps. Nothing to install.
verify_a2a_agent_card is a Read tool with low risk. Read-only tools are generally safe to allow by default.
Yes. Add a rate_limit block to the verify_a2a_agent_card 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 verify_a2a_agent_card. 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.
verify_a2a_agent_card is provided by the Ainumbers Mcp Apps MCP server (postoaklabs/ainumbers-mcp-apps). 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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