update_agents_file · Agents Library MCP Server MCP

WHAT IT DOES

What update_agents_file does on Agents Library MCP Server

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

WHY IT NEEDS A POLICY

Why update_agents_file needs a policy

This tool creates or modifies data (file content) in a reversible manner. While it changes agent instructions/prompts used in AI workflows, the changes are not destructive—files can be reverted, edited again, or restored.

From the tool's definition Tool name 'update_agents_file' and description 'Updates the content of a specific AGENTS.md file' explicitly indicates modification of existing files.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

update_agents_file Rate-limited

update_agents_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_agents_file": {
      "limits": [
        {
          "counter": "update_agents_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 Agents Library MCP Server, so you can run agents against it safely.

FAQ

Questions about update_agents_file

What does the update_agents_file tool do? +

Updates the content of a specific AGENTS.md file in the agents-library. It is categorised as a Write tool in the Agents Library MCP Server 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_agents_file? +

Register the Agents Library MCP Server MCP server in PolicyLayer and add a rule for update_agents_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 Agents Library MCP Server. Nothing to install.

What risk level is update_agents_file? +

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

Can I rate-limit update_agents_file? +

Yes. Add a rate_limit block to the update_agents_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_agents_file completely? +

Set action: deny in the PolicyLayer policy for update_agents_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_agents_file? +

update_agents_file is provided by the Agents Library MCP Server MCP server (nicholaswilde/mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

// THE FULL RECORD

update_agents_file is one line of Agents Library MCP Server's registry record.

The record carries the whole server: verified identity, auth posture, risk grade, every tool classified, recommended policy — re-checked continuously.

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