refresh_index · Eml MCP: Risk & Policy

WHAT IT DOES

What refresh_index does on Eml

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

WHY IT NEEDS A POLICY

Why refresh_index needs a policy

This tool modifies the search/metadata index by adding new entries, removing stale ones, and updating changed files. While 'remove deleted' suggests some destructive-adjacent behavior, it is removing index entries for already-deleted files (not deleting the files themselves), making this primarily a Write/maintenance operation on the index data structure.

From the tool's definition Incrementally update the index: add new, remove deleted, update changed files

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

refresh_index Rate-limited

refresh_index 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": {
    "refresh_index": {
      "limits": [
        {
          "counter": "refresh_index_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 Eml, so you can run agents against it safely.

FAQ

Questions about refresh_index

What does the refresh_index tool do? +

Incrementally update the index: add new, remove deleted, update changed files. It is categorised as a Write tool in the Eml MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on refresh_index? +

Register the Eml MCP server in PolicyLayer and add a rule for refresh_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 Eml. Nothing to install.

What risk level is refresh_index? +

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

Can I rate-limit refresh_index? +

Yes. Add a rate_limit block to the refresh_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 refresh_index completely? +

Set action: deny in the PolicyLayer policy for refresh_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 refresh_index? +

refresh_index is provided by the Eml MCP server (miguelripoll23/eml-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.