save_session · Strudel MCP: Risk & Policy

WHAT IT DOES

What save_session does on Strudel

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

WHY IT NEEDS A POLICY

Why save_session needs a policy

This tool writes/persists session data to storage, making it a Write operation. It is reversible (sessions can be re-saved or deleted by other means) and has no financial impact. Severity is medium because an agent could inadvertently save corrupted or unwanted session states, but the context of a music live-coding environment means the blast radius is limited to that session's data, not system-wide resources.

From the tool's definition Tool name 'save_session' combined with description 'Save a session to storage' indicates a write operation that persists data to storage. The tool creates or modifies stored session state.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

save_session Rate-limited

save_session 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": {
    "save_session": {
      "limits": [
        {
          "counter": "save_session_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 Strudel, so you can run agents against it safely.

FAQ

Questions about save_session

What does the save_session tool do? +

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

How do I enforce a policy on save_session? +

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

What risk level is save_session? +

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

Can I rate-limit save_session? +

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

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

save_session is provided by the Strudel MCP server (utenadev/strudel-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.