permission_set · LocalAnt MCP: Risk & Policy

WHAT IT DOES

What permission_set does on LocalAnt

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

WHY IT NEEDS A POLICY

Why permission_set needs a policy

This tool modifies the security permission model of the MCP gateway itself — changing which directories, commands, and modes are allowed. While technically a 'Write' (reversible update), the blast radius is critical: an AI agent misusing this tool could expand its own permissions to allow arbitrary shell commands or unrestricted file access, effectively bypassing all safety controls on the system.

From the tool's definition "Update security permissions (mode / allowedDirectories / allowedCommands)"

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

permission_set Rate-limited

permission_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": {
    "permission_set": {
      "limits": [
        {
          "counter": "permission_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 LocalAnt, so you can run agents against it safely.

FAQ

Questions about permission_set

What does the permission_set tool do? +

Update security permissions (mode / allowedDirectories / allowedCommands). It is categorised as a Write tool in the LocalAnt MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on permission_set? +

Register the LocalAnt MCP server in PolicyLayer and add a rule for permission_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 LocalAnt. Nothing to install.

What risk level is permission_set? +

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

Can I rate-limit permission_set? +

Yes. Add a rate_limit block to the permission_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 permission_set completely? +

Set action: deny in the PolicyLayer policy for permission_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 permission_set? +

permission_set is provided by the LocalAnt MCP server (yuga-hashimoto/localant). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.