rebuild_index · Cursor MCP Server MCP: Risk & Policy

WHAT IT DOES

What rebuild_index does on Cursor MCP Server

AI agents invoke rebuild_index to trigger actions in Cursor MCP Server. 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 rebuild_index needs a policy

Rebuilding an index is an operation that runs a computational process (scanning and re-indexing all project files) with side effects on the ChromaDB index store. It does not simply read data, nor does it irreversibly delete user content (it replaces/rebuilds an index, which is recoverable). It qualifies as Execute because it triggers an external operation (ChromaDB re-indexing) whose scope depends on the project.

From the tool's definition 'Rebuild the semantic code index (ChromaDB) for the entire project' — triggers a full re-indexing operation across the entire project

Risk signalsBulk/mass operation — affects multiple targets

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

rebuild_index Rate-limited

rebuild_index 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": {
    "rebuild_index": {
      "limits": [
        {
          "counter": "rebuild_index_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 Cursor MCP Server, so you can run agents against it safely.

FAQ

Questions about rebuild_index

What does the rebuild_index tool do? +

Rebuild the semantic code index (ChromaDB) for the entire project. It is categorised as a Execute tool in the Cursor MCP Server MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on rebuild_index? +

Register the Cursor MCP Server MCP server in PolicyLayer and add a rule for rebuild_index: 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 Cursor MCP Server. Nothing to install.

What risk level is rebuild_index? +

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

Can I rate-limit rebuild_index? +

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

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

rebuild_index is provided by the Cursor MCP Server MCP server (tariqnasheed/cursor_mcp_server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.