steady_set_cookies · Steady MCP: Risk & Policy

WHAT IT DOES

What steady_set_cookies does on Steady MCP

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

WHY IT NEEDS A POLICY

Why steady_set_cookies needs a policy

This tool creates/modifies authentication state by persisting cookie values locally. While it does not directly access external data (Read), execute code (Execute), delete data (Destructive), or move money (Financial), it does persistently alter the client's stored credentials in a way that subsequent tools depend on. This is a Write operation because it reversibly modifies local authentication state.

From the tool's definition 'Store Steady cookies (Cookie header value) locally' — this tool writes authentication tokens to local storage, modifying the client's authentication state. The description explicitly states it stores cookie values persistently.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

steady_set_cookies Rate-limited

steady_set_cookies 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": {
    "steady_set_cookies": {
      "limits": [
        {
          "counter": "steady_set_cookies_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 Steady MCP, so you can run agents against it safely.

FAQ

Questions about steady_set_cookies

What does the steady_set_cookies tool do? +

Store Steady cookies (Cookie header value) locally so other tools can authenticate. Provide at least remember_user_token and/or _sthr_session. It is categorised as a Write tool in the Steady MCP MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on steady_set_cookies? +

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

What risk level is steady_set_cookies? +

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

Can I rate-limit steady_set_cookies? +

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

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

steady_set_cookies is provided by the Steady MCP server (sarthak-ignite/steady-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.