join_arena · Lichess Integration MCP: Risk & Policy

WHAT IT DOES

What join_arena does on Lichess Integration

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

PARAMETERS

Parameter	Type	Required	Description
`tournamentId`	string	—	Tournament ID

Parameters from the server's own tool schema.

WHY IT NEEDS A POLICY

Why join_arena needs a policy

Joining an arena tournament creates a participation record and commits the user to the tournament. This is a reversible write action (you can typically withdraw), not destructive or financial. Misuse could result in unwanted tournament registrations.

From the tool's definition Join an arena tournament

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

join_arena Rate-limited

join_arena 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": {
    "join_arena": {
      "limits": [
        {
          "counter": "join_arena_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 Lichess Integration, so you can run agents against it safely.

FAQ

Questions about join_arena

What does the join_arena tool do? +

Join an arena tournament. It is categorised as a Write tool in the Lichess Integration MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

What parameters does join_arena accept? +

join_arena accepts 1 parameter: tournamentId. The full parameter table on this page comes from the server's own tool schema.

How do I enforce a policy on join_arena? +

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

What risk level is join_arena? +

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

Can I rate-limit join_arena? +

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

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

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