update_file · Kontexta MCP: Risk & Policy

WHAT IT DOES

What update_file does on Kontexta

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

WHY IT NEEDS A POLICY

Why update_file needs a policy

This tool modifies file content reversibly. It is Write rather than Destructive because the operation is theoretically reversible (previous versions can be recovered via git, as indicated by the server's 'git-backed' architecture). However, severity is high because careless replacement of file content could corrupt important knowledge vault entries or configuration files.

From the tool's definition Tool description states 'Update the entire content of an existing file by its ID. This replaces the file' — explicit modification of existing data.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

update_file Rate-limited

update_file 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_file": {
      "limits": [
        {
          "counter": "update_file_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 Kontexta, so you can run agents against it safely.

FAQ

Questions about update_file

What does the update_file tool do? +

Update the entire content of an existing file by its ID. This replaces the file. It is categorised as a Write tool in the Kontexta 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_file? +

Register the Kontexta MCP server in PolicyLayer and add a rule for update_file: 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 Kontexta. Nothing to install.

What risk level is update_file? +

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

Can I rate-limit update_file? +

Yes. Add a rate_limit block to the update_file 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_file completely? +

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

update_file is provided by the Kontexta MCP server (safiyu/kontexta). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.