AI agents use apply_patch to create or update resources in Coding Tools MCP — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Coding Tools MCP environment.
Applying a patch modifies file contents within a repository, which is a reversible Write operation. While not Destructive (patches can be reverted), it has high severity because an AI agent could apply malicious or incorrect patches to code, affecting multiple files and potentially compromising the codebase.
From the tool's definition Tool named 'apply_patch' on a coding tools server with sibling tools including git operations (git_diff, git_show, git_status), indicating version control context. Patch application modifies files in a repository. Description is empty but context is clear.
Documented attack patterns abuse exactly the kind of access apply_patch gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Coding Tools MCP, and nothing reaches the server without passing your rules. This is the rule we recommend for apply_patch:
{
"version": "1",
"default": "deny",
"tools": {
"apply_patch": {
"limits": [
{
"counter": "apply_patch_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}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.
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apply_patch. It is categorised as a Write tool in the Coding Tools MCP MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Coding Tools 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 Tools MCP. Nothing to install.
apply_patch is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.
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.
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.
apply_patch is provided by the Coding Tools MCP server (xytom/coding-tools-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 18 Coding Tools MCP tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
Free to start. No card required.
18 Coding Tools MCP tools catalogued and risk-classified — across an index of 42,500+ MCP servers.