Check and retrieve messages
AI agents call check_messages 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 messages from the Redis-backed coordination system without creating, modifying, or deleting data. In the context of a multi-agent collaboration server, checking messages is a passive intelligence-gathering operation essential for agents to stay synchronized.
From the tool's definition Tool name 'check_messages' and description 'Check and retrieve messages' indicate a retrieval operation with no modification or side effects. The verb 'check and retrieve' aligns with Read category operations.
Documented attack patterns abuse exactly the kind of access check_messages 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 check_messages:
{
"version": "1",
"default": "deny",
"tools": {
"check_messages": {}
}
}check_messages is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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Check and retrieve messages. 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 check_messages: 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.
check_messages 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 check_messages 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 check_messages. 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.
check_messages 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.