add_pattern_to_session · Strudel MCP: Risk & Policy

WHAT IT DOES

What add_pattern_to_session does on Strudel

AI agents use add_pattern_to_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 add_pattern_to_session needs a policy

This tool creates or modifies session data by adding a pattern, which is a reversible operation. It does not execute arbitrary code (that would be execute_strudel_code), delete data (destructive), or retrieve data (read). The severity is medium because misuse could modify a user's music session unexpectedly, but the effect is reversible—patterns can be removed or the session reset.

From the tool's definition Tool name 'add_pattern_to_session' and description 'Add a pattern to the current session' indicate modification of session state. In the context of a live coding music environment, adding patterns is a state-changing operation.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

add_pattern_to_session Rate-limited

add_pattern_to_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": {
    "add_pattern_to_session": {
      "limits": [
        {
          "counter": "add_pattern_to_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 add_pattern_to_session

What does the add_pattern_to_session tool do? +

Add a pattern to the current session. 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 add_pattern_to_session? +

Register the Strudel MCP server in PolicyLayer and add a rule for add_pattern_to_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 add_pattern_to_session? +

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

Can I rate-limit add_pattern_to_session? +

Yes. Add a rate_limit block to the add_pattern_to_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 add_pattern_to_session completely? +

Set action: deny in the PolicyLayer policy for add_pattern_to_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 add_pattern_to_session? +

add_pattern_to_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.