lichess_auth_start · Lichess MCP: Risk & Policy

WHAT IT DOES

What lichess_auth_start does on Lichess MCP

AI agents invoke lichess_auth_start to trigger actions in Lichess MCP. 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 lichess_auth_start needs a policy

This tool executes an external operation (opening a browser and initiating an OAuth flow) rather than simply reading or writing data directly. While the operation itself is reversible and not financially damaging, it causes side effects by launching a browser process and modifying authentication state.

From the tool's definition Tool description states it 'Opens a browser for authorization' and 'authenticate your Lichess chess account', indicating it triggers an external browser operation whose effects depend on user interaction and the resulting OAuth token state.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

lichess_auth_start Rate-limited

lichess_auth_start 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": {
    "lichess_auth_start": {
      "limits": [
        {
          "counter": "lichess_auth_start_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 Lichess MCP, so you can run agents against it safely.

FAQ

Questions about lichess_auth_start

What does the lichess_auth_start tool do? +

Start the Lichess OAuth login flow. Opens a browser for authorization. Use this to connect, sign in, or authenticate your Lichess chess account. It is categorised as a Execute tool in the Lichess MCP MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on lichess_auth_start? +

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

What risk level is lichess_auth_start? +

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

Can I rate-limit lichess_auth_start? +

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

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

lichess_auth_start is provided by the Lichess MCP server (jamespdaily/lichess-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.