swarm_modify_file · Mcp Swarm MCP: Risk & Policy

WHAT IT DOES

What swarm_modify_file does on Mcp Swarm

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

WHY IT NEEDS A POLICY

Why swarm_modify_file needs a policy

This tool creates or modifies file content via find-and-replace operations. While backups are mentioned (suggesting reversibility), AI agents could misuse this to corrupt source code, configuration files, or other critical content. The blast radius is significant in a development environment where file modifications could affect build systems, deployments, or application logic.

From the tool's definition Tool description states '智能修改文件内容（查找替换）' which translates to 'intelligently modify file content (find and replace)'. This is an explicit content modification operation.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

swarm_modify_file Rate-limited

swarm_modify_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": {
    "swarm_modify_file": {
      "limits": [
        {
          "counter": "swarm_modify_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 Mcp Swarm, so you can run agents against it safely.

FAQ

Questions about swarm_modify_file

What does the swarm_modify_file tool do? +

智能修改文件内容（查找替换）。会先备份现有文件。. It is categorised as a Write tool in the Mcp Swarm MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on swarm_modify_file? +

Register the Mcp Swarm MCP server in PolicyLayer and add a rule for swarm_modify_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 Mcp Swarm. Nothing to install.

What risk level is swarm_modify_file? +

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

Can I rate-limit swarm_modify_file? +

Yes. Add a rate_limit block to the swarm_modify_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 swarm_modify_file completely? +

Set action: deny in the PolicyLayer policy for swarm_modify_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 swarm_modify_file? +

swarm_modify_file is provided by the Mcp Swarm MCP server (moselu/mcp-swarm). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.