update_session_summary · MCP Session Closer MCP

WHAT IT DOES

What update_session_summary does on MCP Session Closer

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

WHY IT NEEDS A POLICY

Why update_session_summary needs a policy

This tool writes/modifies a session summary file. While it updates state (placing it in the Write category), the blast radius is medium rather than high because: (1) it operates on a summary/metadata file rather than critical application data, (2) updates are typically reversible (can be re-written), and (3) the scope is local to session documentation.

From the tool's definition Tool description states it 'Update[s] the session summary file with current session info' - an explicit modification operation. The term 'update' indicates reversible data modification rather than deletion or irreversible changes.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

update_session_summary Rate-limited

update_session_summary 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": {
    "update_session_summary": {
      "limits": [
        {
          "counter": "update_session_summary_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 MCP Session Closer, so you can run agents against it safely.

FAQ

Questions about update_session_summary

What does the update_session_summary tool do? +

Update the session summary file with current session info without doing a full session close. It is categorised as a Write tool in the MCP Session Closer MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on update_session_summary? +

Register the MCP Session Closer MCP server in PolicyLayer and add a rule for update_session_summary: 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 MCP Session Closer. Nothing to install.

What risk level is update_session_summary? +

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

Can I rate-limit update_session_summary? +

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

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

update_session_summary is provided by the MCP Session Closer MCP server (tylarcam/mcp-session-closer). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.