fail · Code Mode Bridge MCP: Risk & Policy

WHAT IT DOES

What fail does on Code Mode Bridge

AI agents call fail as a supporting operation in Code Mode Bridge workflows.

WHY IT NEEDS A POLICY

Why fail needs a policy

The tool is described as one that 'always fails', meaning it produces no successful side effects — no data is read, written, executed, or deleted. Its only observable behavior is returning an error. This makes it genuinely 'Other'. Confidence is moderate because the description is minimal and potentially misleading, but taken at face value, it does nothing harmful.

From the tool's definition A tool that always fails

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

fail Rate-limited

fail gets a rate cap, and everything else on the server is denied unless you say otherwise.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "fail": {
      "limits": [
        {
          "counter": "fail_rate",
          "window": "minute",
          "max": 60,
          "scope": "grant"
        }
      ]
    }
  }
}

SET A RULE FOR THIS TOOL →

Instant setup, no code required.

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

FAQ

Questions about fail

What does the fail tool do? +

A tool that always fails. It is categorised as a Other tool in the Code Mode Bridge MCP Server, which means it performs auxiliary operations.

How do I enforce a policy on fail? +

Register the Code Mode Bridge MCP server in PolicyLayer and add a rule for fail: 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 Code Mode Bridge. Nothing to install.

What risk level is fail? +

fail is a Other tool with low risk. Read-only tools are generally safe to allow by default.

Can I rate-limit fail? +

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

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

fail is provided by the Code Mode Bridge MCP server (ruifung/mcp-cm-bridge). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.