High Risk →

mypy

Runs mypy and returns structured type-check diagnostics (file, line, severity, message, code).

How to control mypy ↓

What mypy does on Http

AI agents invoke mypy to trigger actions in Http. 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.

High Risk

Why mypy needs a policy

This tool executes an external program (mypy) on code files. While mypy itself is a read-only static analysis tool, it runs arbitrary external processes which constitutes Execute category. The blast radius is medium: an attacker could point it at sensitive files or use it to probe the file system, but it does not modify or delete data.

From the tool's definition 'Runs mypy' — executes the mypy static type checker as an external process and returns its output

Documented attack patterns abuse exactly the kind of access mypy gives an agent:

How to control mypy

PolicyLayer is an MCP gateway — it sits between your AI agents and Http, and nothing reaches the server without passing your rules. This is the rule we recommend for mypy:

policy.json
{
  "version": "1",
  "default": "deny",
  "tools": {
    "mypy": {
      "limits": [
        {
          "counter": "mypy_rate",
          "window": "minute",
          "max": 10,
          "scope": "grant"
        }
      ]
    }
  }
}

mypy 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.

  1. Create a free account and register Http — nothing to install.
  2. Add this policy — paste it, or build it visually.
  3. Point your MCP client (Claude, Cursor, anything) at your gateway URL.
RATE-LIMIT THIS TOOL →

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Related tools and policies

Go deeper

Questions about mypy

What does the mypy tool do? +

Runs mypy and returns structured type-check diagnostics (file, line, severity, message, code). It is categorised as a Execute tool in the Http MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on mypy? +

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

What risk level is mypy? +

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

Can I rate-limit mypy? +

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

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

mypy is provided by the Http MCP server (@paretools/http). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every Http tool call.

Start from Http, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.

Free to start. No card required.

202 Http tools catalogued and risk-classified — across an index of 43,000+ MCP servers.

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