mark_session_failed · Repl MCP: Risk & Policy

WHAT IT DOES

What mark_session_failed does on Repl

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

WHY IT NEEDS A POLICY

Why mark_session_failed needs a policy

An AI agent can call mark_session_failed faster than any human can review — one bad instruction and it creates or modifies resources in Repl by the hundred, each call as confident as the last.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

mark_session_failed Rate-limited

mark_session_failed 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": {
    "mark_session_failed": {
      "limits": [
        {
          "counter": "mark_session_failed_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 Repl, so you can run agents against it safely.

FAQ

Questions about mark_session_failed

What does the mark_session_failed tool do? +

Mark a session as failed with a specific reason. Used during LLM-assisted session recovery when recovery is not possible. It is categorised as a Write tool in the Repl MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on mark_session_failed? +

Register the Repl MCP server in PolicyLayer and add a rule for mark_session_failed: 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 Repl. Nothing to install.

What risk level is mark_session_failed? +

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

Can I rate-limit mark_session_failed? +

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

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

mark_session_failed is provided by the Repl MCP server (takafu/repl-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.