Reply to an existing A2A task and optionally update its status. Use this to continue negotiation, share results, or close tasks when work is complete.
Part of the AgentTrust — Identity & Trust for A2A Agents server.
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AI agents use agenttrust_reply to create or modify resources in AgentTrust — Identity & Trust for A2A Agents. Write operations carry medium risk because an autonomous agent could trigger bulk unintended modifications. Rate limits prevent a single agent session from making hundreds of changes in rapid succession. Argument validation ensures the agent passes expected values.
Without a policy, an AI agent could call agenttrust_reply repeatedly, creating or modifying resources faster than any human could review. PolicyLayer's rate limiting ensures write operations happen at a controlled pace, and argument validation catches malformed or unexpected inputs before they reach AgentTrust — Identity & Trust for A2A Agents.
Write tools can modify data. A rate limit prevents runaway bulk operations from AI agents.
{
"version": "1",
"default": "deny",
"tools": {
"agenttrust_reply": {
"limits": [
{
"counter": "agenttrust_reply_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}See the full AgentTrust — Identity & Trust for A2A Agents policy for all 19 tools.
These attack patterns abuse exactly the kind of access agenttrust_reply gives an agent. Each links to the full case and the policy that stops it:
Other write tools across the catalogue. The same approach applies to each: rate-limit and validate the arguments.
Reply to an existing A2A task and optionally update its status. Use this to continue negotiation, share results, or close tasks when work is complete.. It is categorised as a Write tool in the AgentTrust — Identity & Trust for A2A Agents MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the AgentTrust — Identity & Trust for A2A Agents MCP server in PolicyLayer and add a rule for agenttrust_reply: 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 AgentTrust — Identity & Trust for A2A Agents. Nothing to install.
agenttrust_reply is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.
Yes. Add a rate_limit block to the agenttrust_reply 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 agenttrust_reply. 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.
agenttrust_reply is provided by the AgentTrust — Identity & Trust for A2A Agents MCP server (@agenttrust/mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 19 AgentTrust — Identity & Trust for A2A Agents tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
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