Query an A2A task to get its current status, messages, and artifacts. Optionally limit how much conversation history is returned.
Part of the Agent0 server.
Free to start. No card required.
AI agents call a2a_query_task to retrieve information from Agent0 without modifying any data. This is common in research, monitoring, and reporting workflows where the agent needs context before taking action. Because read operations don't change state, they are generally safe to allow without restrictions -- but you may still want rate limits to control API costs.
Even though a2a_query_task only reads data, uncontrolled read access can leak sensitive information or rack up API costs. An agent caught in a retry loop could make thousands of calls per minute. A rate limit gives you a safety net without blocking legitimate use.
Read-only tools are safe to allow by default. No rate limit needed unless you want to control costs.
{
"version": "1",
"default": "deny",
"tools": {
"a2a_query_task": {}
}
}See the full Agent0 policy for all 34 tools.
These attack patterns abuse exactly the kind of access a2a_query_task gives an agent. Each links to the full case and the policy that stops it:
Other read tools across the catalogue. The same approach applies to each: allow, with a rate cap to control cost.
Query an A2A task to get its current status, messages, and artifacts. Optionally limit how much conversation history is returned.. It is categorised as a Read tool in the Agent0 MCP Server, which means it retrieves data without modifying state.
Register the Agent0 MCP server in PolicyLayer and add a rule for a2a_query_task: 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 Agent0. Nothing to install.
a2a_query_task 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 a2a_query_task 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 a2a_query_task. 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.
a2a_query_task is provided by the Agent0 MCP server (@rickydata/agent0-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 34 Agent0 tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
Free to start. No card required.
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