modify_files · Claude Code Control MCP: Risk & Policy

WHAT IT DOES

What modify_files does on Claude Code Control MCP

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

WHY IT NEEDS A POLICY

Why modify_files needs a policy

This tool modifies (creates or updates) file contents in batch. While the description is truncated ('Provides batch file' is incomplete), the name and stated function clearly indicate write operations on multiple files. This is categorized as Write rather than Destructive because modification is typically reversible (files can be reverted, edited again, or restored from version control).

From the tool's definition Tool name is 'modify_files' and description states 'Modify multiple files with specified changes. Provides batch file' — the verb 'modify' and explicit purpose to change files indicates reversible data modification.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

modify_files Rate-limited

modify_files 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": {
    "modify_files": {
      "limits": [
        {
          "counter": "modify_files_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 Code Control MCP, so you can run agents against it safely.

FAQ

Questions about modify_files

What does the modify_files tool do? +

Modify multiple files with specified changes. Provides batch file. It is categorised as a Write tool in the Claude Code Control MCP MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on modify_files? +

Register the Claude Code Control MCP server in PolicyLayer and add a rule for modify_files: 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 Code Control MCP. Nothing to install.

What risk level is modify_files? +

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

Can I rate-limit modify_files? +

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

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

modify_files is provided by the Claude Code Control MCP server (marc-shade/claude-code-control-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.