start_session · Claude DJ MCP: Risk & Policy

WHAT IT DOES

What start_session does on Claude DJ MCP

AI agents invoke start_session to trigger actions in Claude DJ MCP. What it does depends on the arguments the agent supplies, and its effects often reach beyond the immediate call — builds kicked off, notifications sent, workflows started.

WHY IT NEEDS A POLICY

Why start_session needs a policy

start_session initiates an HTTP server and audio engine, which are external operations with side effects that persist until explicitly stopped. This constitutes an Execute action rather than Read (no query), Write (not data creation/modification in traditional sense), or Destructive (reversible via stop_music).

From the tool's definition Tool "launches HTTP server and initializes the audio engine" - these are operations that trigger external processes and state changes whose effects depend on network conditions and configuration.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

start_session Rate-limited

start_session stays usable, but rate-capped — a runaway agent can't fire it dozens of times a minute. Everything else on the server is denied unless you say otherwise.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "start_session": {
      "limits": [
        {
          "counter": "start_session_rate",
          "window": "minute",
          "max": 10,
          "scope": "grant"
        }
      ]
    }
  }
}

RATE-LIMIT THIS TOOL →

Instant setup, no code required.

PolicyLayer is an MCP gateway: every tool call is checked against your rule before it reaches Claude DJ MCP, so you can run agents against it safely.

FAQ

Questions about start_session

What does the start_session tool do? +

Start a DJ session: launches HTTP server and initializes the audio engine. Returns stream URL with LAN IP. Anyone on the network can tune in. It is categorised as a Execute tool in the Claude DJ MCP MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on start_session? +

Register the Claude DJ MCP server in PolicyLayer and add a rule for start_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 Claude DJ MCP. Nothing to install.

What risk level is start_session? +

start_session is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.

Can I rate-limit start_session? +

Yes. Add a rate_limit block to the start_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 start_session completely? +

Set action: deny in the PolicyLayer policy for start_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 start_session? +

start_session is provided by the Claude DJ MCP server (uetuluk/claude-dj-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.