variable-set · Python MCP: Risk & Policy

WHAT IT DOES

What variable-set does on Python

AI agents use variable-set to create or update resources in Python — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Python environment.

WHY IT NEEDS A POLICY

Why variable-set needs a policy

This tool creates or modifies GitHub Actions variables, which are persistent configuration changes. While not destructive (changes are reversible by overwriting), it is a Write operation that alters system state. Severity is high because misconfigured variables can affect CI/CD pipelines, potentially causing deployment failures or exposing sensitive information in logs if misused by an agent.

From the tool's definition Tool description states it 'Sets a repository, organization, or environment GitHub Actions variable.' The verb 'Sets' indicates modification/creation of configuration state.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

variable-set Rate-limited

variable-set 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": {
    "variable-set": {
      "limits": [
        {
          "counter": "variable-set_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 Python, so you can run agents against it safely.

FAQ

Questions about variable-set

What does the variable-set tool do? +

Sets a repository, organization, or environment GitHub Actions variable. Variables are not secret and may be visible in logs. It is categorised as a Write tool in the Python MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on variable-set? +

Register the Python MCP server in PolicyLayer and add a rule for variable-set: 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 variable-set? +

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

Can I rate-limit variable-set? +

Yes. Add a rate_limit block to the variable-set 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 variable-set completely? +

Set action: deny in the PolicyLayer policy for variable-set. 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 variable-set? +

variable-set 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.