update_index · Wiki MCP: Risk & Policy

WHAT IT DOES

What update_index does on Wikimcp

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

WHY IT NEEDS A POLICY

Why update_index needs a policy

This tool modifies the wiki's index file (a reversible write operation). Although it overwrites existing content, the git-backed nature of the system means the previous version remains recoverable via version control, preventing it from being classified as Destructive. The impact is scoped to the index file rather than arbitrary code execution.

From the tool's definition Tool description states "Overwrite index.md with new content and auto-commit." The verb "overwrite" indicates modification of existing data, while "auto-commit" shows the change is persisted to git.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

update_index Rate-limited

update_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": {
    "update_index": {
      "limits": [
        {
          "counter": "update_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 Wikimcp, so you can run agents against it safely.

FAQ

Questions about update_index

What does the update_index tool do? +

Overwrite index.md with new content and auto-commit. It is categorised as a Write tool in the Wikimcp MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on update_index? +

Register the Wiki MCP server in PolicyLayer and add a rule for update_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 Wikimcp. Nothing to install.

What risk level is update_index? +

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

Can I rate-limit update_index? +

Yes. Add a rate_limit block to the update_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 update_index completely? +

Set action: deny in the PolicyLayer policy for update_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 update_index? +

update_index is provided by the Wiki MCP server (mohith-das/wikimcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.