shellcheck · Python MCP: Risk & Policy

WHAT IT DOES

What shellcheck does on Python

AI agents invoke shellcheck to trigger actions in Python. 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 shellcheck needs a policy

This tool executes an external process (ShellCheck) against shell scripts. While it is read-only in intent (linting), it runs arbitrary external commands on files/scripts provided as arguments. The blast radius is high because a malicious actor could point it at sensitive files or use it as a stepping stone to understand shell scripts for further exploitation. The key term 'Runs' confirms external execution.

From the tool's definition Runs ShellCheck (shell script linter) and returns structured diagnostics

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

shellcheck Rate-limited

shellcheck 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": {
    "shellcheck": {
      "limits": [
        {
          "counter": "shellcheck_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 Python, so you can run agents against it safely.

FAQ

Questions about shellcheck

What does the shellcheck tool do? +

Runs ShellCheck (shell script linter) and returns structured diagnostics (file, line, column, rule, severity, message). It is categorised as a Execute tool in the Python MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on shellcheck? +

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

What risk level is shellcheck? +

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

Can I rate-limit shellcheck? +

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

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

shellcheck is provided by the Python MCP server (Dave-London/Pare). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

// THE FULL RECORD

shellcheck is one line of Python's registry record.

The record carries the whole server: verified identity, auth posture, risk grade, every tool classified, recommended policy — re-checked continuously.

Teams ship this data inside their own products. See what a licence covers →