Get shared interface definition
AI agents call query_interface to retrieve information from A2AMCP without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool retrieves/reads shared interface definitions in a Redis-backed coordination server. It has no side effects—it only fetches existing data. The blast radius if misused is minimal; an agent might retrieve interface definitions it shouldn't access, but cannot execute code, modify data, delete resources, or move money. Classified as Read with low severity.
From the tool's definition Tool name 'query_interface' and description 'Get shared interface definition' indicate a retrieval operation that queries and returns interface metadata without modifying or executing anything.
Documented attack patterns abuse exactly the kind of access query_interface gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and A2AMCP, and nothing reaches the server without passing your rules. This is the rule we recommend for query_interface:
{
"version": "1",
"default": "deny",
"tools": {
"query_interface": {}
}
}query_interface is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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Get shared interface definition. It is categorised as a Read tool in the A2AMCP MCP Server, which means it retrieves data without modifying state.
Register the A2A MCP server in PolicyLayer and add a rule for query_interface: 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 A2AMCP. Nothing to install.
query_interface 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 query_interface 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 query_interface. 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.
query_interface is provided by the A2A MCP server (webdevtodayjason/a2amcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from A2AMCP, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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17 A2AMCP tools catalogued and risk-classified — across an index of 43,000+ MCP servers.