index_project · Rails Insight MCP: Risk & Policy

WHAT IT DOES

What index_project does on Rails Insight

AI agents invoke index_project to trigger actions in Rails Insight. 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 index_project needs a policy

This tool triggers an active re-scanning and re-indexing operation on the project filesystem. It performs an external operation (file system scan and index rebuild) whose effects depend on the current state of the project. It's not purely reading existing indexed data (like the other 'get_*' tools), nor is it destructive or financial.

From the tool's definition Re-index the Rails project. In local mode, re-scans the project root.

Risk signalsAdmin/system-level operation

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

index_project Rate-limited

index_project 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": {
    "index_project": {
      "limits": [
        {
          "counter": "index_project_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 Rails Insight, so you can run agents against it safely.

FAQ

Questions about index_project

What does the index_project tool do? +

Re-index the Rails project. In local mode, re-scans the project root. Returns statistics and duration. It is categorised as a Execute tool in the Rails Insight MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on index_project? +

Register the Rails Insight MCP server in PolicyLayer and add a rule for index_project: 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 Rails Insight. Nothing to install.

What risk level is index_project? +

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

Can I rate-limit index_project? +

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

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

index_project is provided by the Rails Insight MCP server (@reinteractive/rails-insight). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.