reply · Agent Link MCP: Risk & Policy

WHAT IT DOES

What reply does on Agent Link

AI agents invoke reply to trigger actions in Agent Link. What it does depends on the arguments the agent supplies, and its effects often reach beyond the immediate call — builds kicked off, notifications sent, workflows started.

WHY IT NEEDS A POLICY

Why reply needs a policy

This tool sends input to a running agent process and drives its continued execution. The downstream effects depend entirely on what the agent does with the reply — it could trigger arbitrary operations (writes, deletions, API calls, etc.) depending on the agent's task. Since it resumes and directs execution of an external agent CLI, it falls under Execute.

From the tool's definition 'Reply to an agent that is waiting for clarification. Continues the conversation until the agent returns a result or asks another question.'

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

reply Rate-limited

reply stays usable, but rate-capped — a runaway agent can't fire it dozens of times a minute. Everything else on the server is denied unless you say otherwise.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "reply": {
      "limits": [
        {
          "counter": "reply_rate",
          "window": "minute",
          "max": 10,
          "scope": "grant"
        }
      ]
    }
  }
}

RATE-LIMIT THIS TOOL →

Instant setup, no code required.

PolicyLayer is an MCP gateway: every tool call is checked against your rule before it reaches Agent Link, so you can run agents against it safely.

FAQ

Questions about reply

What does the reply tool do? +

Reply to an agent that is waiting for clarification. Continues the conversation until the agent returns a result or asks another question. It is categorised as a Execute tool in the Agent Link MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on reply? +

Register the Agent Link MCP server in PolicyLayer and add a rule for 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 Agent Link. Nothing to install.

What risk level is reply? +

reply is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.

Can I rate-limit reply? +

Yes. Add a rate_limit block to the 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.

How do I block reply completely? +

Set action: deny in the PolicyLayer policy for 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.

What MCP server provides reply? +

reply is provided by the Agent Link MCP server (mikusnuz/agent-link-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.