a2a_set_skills · Wmux MCP: Risk & Policy

WHAT IT DOES

What a2a_set_skills does on Wmux

AI agents use a2a_set_skills to create or update resources in Wmux — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Wmux environment.

WHY IT NEEDS A POLICY

Why a2a_set_skills needs a policy

This tool creates or updates skill/capability metadata for agent discovery, which is a Write operation (reversible data modification). Severity is medium because misconfiguration or registration of false capabilities could mislead other agents in the system, but it does not directly execute code, delete data, or move money.

From the tool's definition Tool description states 'Register your agent capabilities/skills', and 'register' indicates creating or modifying metadata about agent capabilities in a registry or discovery system.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

a2a_set_skills Rate-limited

a2a_set_skills stays usable, but capped — an agent stuck in a loop can't make hundreds of changes a minute. Everything else on the server is denied unless you say otherwise.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "a2a_set_skills": {
      "limits": [
        {
          "counter": "a2a_set_skills_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

LIMIT THIS TOOL →

Instant setup, no code required.

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

FAQ

Questions about a2a_set_skills

What does the a2a_set_skills tool do? +

Register your agent capabilities/skills so other agents can discover you via a2a_discover. It is categorised as a Write tool in the Wmux MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on a2a_set_skills? +

Register the Wmux MCP server in PolicyLayer and add a rule for a2a_set_skills: 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 Wmux. Nothing to install.

What risk level is a2a_set_skills? +

a2a_set_skills is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.

Can I rate-limit a2a_set_skills? +

Yes. Add a rate_limit block to the a2a_set_skills 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 a2a_set_skills completely? +

Set action: deny in the PolicyLayer policy for a2a_set_skills. 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 a2a_set_skills? +

a2a_set_skills is provided by the Wmux MCP server (openwong2kim/wmux). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.