ask_best · Agent Bus MCP: Risk & Policy

WHAT IT DOES

What ask_best does on Agent Bus

AI agents invoke ask_best to trigger actions in Agent Bus. 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 ask_best needs a policy

This tool triggers an external operation by routing a message/request to another agent based on capability matching. It doesn't merely read data — it initiates communication and potentially delegates work to another agent, which constitutes executing an action with side effects that depend on the arguments provided (the capability and the message content).

From the tool's definition Route an ask to the most recently-active agent that has the given capability

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

ask_best Rate-limited

ask_best 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": {
    "ask_best": {
      "limits": [
        {
          "counter": "ask_best_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 Bus, so you can run agents against it safely.

FAQ

Questions about ask_best

What does the ask_best tool do? +

Route an ask to the most recently-active agent that has the given capability. It is categorised as a Execute tool in the Agent Bus MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on ask_best? +

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

What risk level is ask_best? +

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

Can I rate-limit ask_best? +

Yes. Add a rate_limit block to the ask_best 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 ask_best completely? +

Set action: deny in the PolicyLayer policy for ask_best. 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 ask_best? +

ask_best is provided by the Agent Bus MCP server (mustaphasteph/agent-bus). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.