apply_patch · Coding MCP Server MCP: Risk & Policy

WHAT IT DOES

What apply_patch does on Coding MCP Server

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

WHY IT NEEDS A POLICY

Why apply_patch needs a policy

Applying a patch modifies existing files by overwriting portions of their content. This is a Write operation (reversible via git), but the blast radius is high because a misapplied patch can corrupt source files across a project. It does not irreversibly delete data on its own (changes can be reverted via git), so Destructive is not chosen, but it ranks high severity due to potential widespread file modification.

From the tool's definition Apply unified diff or structured edits

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

apply_patch Rate-limited

apply_patch 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": {
    "apply_patch": {
      "limits": [
        {
          "counter": "apply_patch_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 Coding MCP Server, so you can run agents against it safely.

FAQ

Questions about apply_patch

What does the apply_patch tool do? +

Apply unified diff or structured edits. It is categorised as a Write tool in the Coding 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 apply_patch? +

Register the Coding MCP Server MCP server in PolicyLayer and add a rule for apply_patch: 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 Coding MCP Server. Nothing to install.

What risk level is apply_patch? +

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

Can I rate-limit apply_patch? +

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

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

apply_patch is provided by the Coding MCP Server MCP server (kieutrongthien/coding-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.