roles_use · Claude Role Library MCP: Risk & Policy

WHAT IT DOES

What roles_use does on Claude Role Library

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

WHY IT NEEDS A POLICY

Why roles_use needs a policy

This tool modifies the active session state by switching the AI persona/role in use. It is a reversible state change (session-scoped, can be changed back), making it a Write operation. Misuse could cause the AI to adopt an unintended or adversarial persona, hence medium severity.

From the tool's definition Activate a role for this session

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

roles_use Rate-limited

roles_use 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": {
    "roles_use": {
      "limits": [
        {
          "counter": "roles_use_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 Claude Role Library, so you can run agents against it safely.

FAQ

Questions about roles_use

What does the roles_use tool do? +

Activate a role for this session. The role\. It is categorised as a Write tool in the Claude Role Library MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on roles_use? +

Register the Claude Role Library MCP server in PolicyLayer and add a rule for roles_use: 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 Claude Role Library. Nothing to install.

What risk level is roles_use? +

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

Can I rate-limit roles_use? +

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

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

roles_use is provided by the Claude Role Library MCP server (tony427/claude-role-library). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.