set_cookie · CTFd MCP Server MCP: Risk & Policy

WHAT IT DOES

What set_cookie does on CTFd MCP Server

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

WHY IT NEEDS A POLICY

Why set_cookie needs a policy

Setting cookies modifies client-side state that affects authentication and session handling. While the description is empty (reducing confidence), the name clearly indicates a write operation that alters session/auth data. This is reversible (cookies can be cleared or overwritten) and not destructive, making it Write rather than Execute.

From the tool's definition Tool name 'set_cookie' indicates modification of cookies, which are state-related data used for authentication and session management in CTFd instances.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

set_cookie Rate-limited

set_cookie 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": {
    "set_cookie": {
      "limits": [
        {
          "counter": "set_cookie_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 CTFd MCP Server, so you can run agents against it safely.

FAQ

Questions about set_cookie

What does the set_cookie tool do? +

set_cookie. It is categorised as a Write tool in the CTFd MCP Server MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on set_cookie? +

Register the CTFd MCP Server MCP server in PolicyLayer and add a rule for set_cookie: 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 CTFd MCP Server. Nothing to install.

What risk level is set_cookie? +

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

Can I rate-limit set_cookie? +

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

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

set_cookie is provided by the CTFd MCP Server MCP server (mrjamescot/ctfd-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.