add_description · MCP Traits Matcher MCP: Risk & Policy

WHAT IT DOES

What add_description does on MCP Traits Matcher

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

WHY IT NEEDS A POLICY

Why add_description needs a policy

This tool modifies data (personality descriptions) but the changes are non-destructive and reversible—descriptions can be updated, edited, or removed later. There is no financial impact, code execution, or irreversible deletion. The blast radius of misuse is limited to potentially incorrect personality profile data, which does not affect external systems or cause harm. This clearly falls under the Write category.

From the tool's definition The tool description states it 'Adds a description to a person, updating their personality.' This is a create or modify operation that updates existing data (the person's personality profile) in a reversible manner.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

add_description Rate-limited

add_description 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": {
    "add_description": {
      "limits": [
        {
          "counter": "add_description_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 MCP Traits Matcher, so you can run agents against it safely.

FAQ

Questions about add_description

What does the add_description tool do? +

Adds a description to a person, updating their personality. It is categorised as a Write tool in the MCP Traits Matcher MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on add_description? +

Register the MCP Traits Matcher MCP server in PolicyLayer and add a rule for add_description: 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 Traits Matcher. Nothing to install.

What risk level is add_description? +

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

Can I rate-limit add_description? +

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

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

add_description is provided by the MCP Traits Matcher MCP server (waifuai/mcp-traits-matcher). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.