start_session · Astria-Index MCP: Risk & Policy

WHAT IT DOES

What start_session does on Astria-Index

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

WHY IT NEEDS A POLICY

Why start_session needs a policy

Based on the server context (AI memory with cross-session continuity) and sibling tools like 'end_session' and 'promote_session', 'start_session' most likely initiates a new memory/context session, which is a Write operation (creating a new session record). Confidence is low due to the empty description — it could also be a Read/Execute depending on implementation.

From the tool's definition Tool name 'start_session'; description is empty and uninformative.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

start_session Rate-limited

start_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": {
    "start_session": {
      "limits": [
        {
          "counter": "start_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 Astria-Index, so you can run agents against it safely.

FAQ

Questions about start_session

What does the start_session tool do? +

start_session. It is categorised as a Write tool in the Astria-Index MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on start_session? +

Register the Astria-Index 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 Astria-Index. Nothing to install.

What risk level is start_session? +

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

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 Astria-Index MCP server (pl-odin/astria-plugin). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.