session_start · Managed Agent Control MCP: Risk & Policy

WHAT IT DOES

What session_start does on Managed Agent Control

AI agents invoke session_start to trigger actions in Managed Agent Control. 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 session_start needs a policy

Starting a managed agent session is an Execute action—it launches an external operation (an agent) that will take actions based on instructions and tool approvals. While not immediately destructive, the blast radius is high because a started agent can then invoke other tools on this server and elsewhere, potentially causing data modification, deletion, or financial transactions depending on agent instructions and…

From the tool's definition Tool named 'session_start' on managed-agent-control-mcp server that 'Start, observe, and interact with Claude Managed Agents.' The description is empty, but the server context indicates this tool initiates agent sessions, which constitutes triggering external…

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

session_start Rate-limited

session_start 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": {
    "session_start": {
      "limits": [
        {
          "counter": "session_start_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 Managed Agent Control, so you can run agents against it safely.

FAQ

Questions about session_start

What does the session_start tool do? +

session_start. It is categorised as a Execute tool in the Managed Agent Control MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on session_start? +

Register the Managed Agent Control MCP server in PolicyLayer and add a rule for session_start: 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 Managed Agent Control. Nothing to install.

What risk level is session_start? +

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

Can I rate-limit session_start? +

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

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

session_start is provided by the Managed Agent Control MCP server (modus-agendi/managed-agent-control-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.