use_skill · MCP Arena MCP: Risk & Policy

WHAT IT DOES

What use_skill does on MCP Arena

AI agents invoke use_skill to trigger actions in MCP Arena. 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 use_skill needs a policy

This tool executes a special in-game combat action (a skill/ability) during a match. It causes state changes in the game world (damage, movement, effects) based on the chosen skill and context. It fits Execute because it triggers an external operation whose effects depend on arguments (which skill is used, timing, target).

From the tool's definition 'Habilidad especial: power_strike (Soldado), smash (Orco), dash_strike (Aventurero)' — triggers special combat skill actions in the arena

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

use_skill Rate-limited

use_skill 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": {
    "use_skill": {
      "limits": [
        {
          "counter": "use_skill_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 MCP Arena, so you can run agents against it safely.

FAQ

Questions about use_skill

What does the use_skill tool do? +

Habilidad especial: power_strike (Soldado), smash (Orco), dash_strike (Aventurero). It is categorised as a Execute tool in the MCP Arena MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on use_skill? +

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

What risk level is use_skill? +

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

Can I rate-limit use_skill? +

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

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

use_skill is provided by the MCP Arena MCP server (jerick97/mcp-arena). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.