write_code · Claude File Management Server MCP

WHAT IT DOES

What write_code does on Claude File Management Server

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

WHY IT NEEDS A POLICY

Why write_code needs a policy

This tool creates or modifies files by writing content to disk. While 'write_code' suggests code files specifically, the mechanism is a general write operation (temp file + atomic replace). The high severity reflects that an AI agent misusing this could overwrite critical application code, configuration files, or system scripts, causing widespread malfunction.

From the tool's definition Tool name 'write_code' and description 'Atomically write content to file_path using a temp file + os.replace' explicitly indicates file creation/modification without deletion.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

write_code Rate-limited

write_code 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": {
    "write_code": {
      "limits": [
        {
          "counter": "write_code_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 Claude File Management Server, so you can run agents against it safely.

FAQ

Questions about write_code

What does the write_code tool do? +

Atomically write content to file_path using a temp file + os.replace. It is categorised as a Write tool in the Claude File Management 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 write_code? +

Register the Claude File Management Server MCP server in PolicyLayer and add a rule for write_code: 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 Claude File Management Server. Nothing to install.

What risk level is write_code? +

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

Can I rate-limit write_code? +

Yes. Add a rate_limit block to the write_code 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 write_code completely? +

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

write_code is provided by the Claude File Management Server MCP server (vipin1000/mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.