Apply multiple search/replace operations to a file in a single atomic operation. Validates all blocks before applying any changes. Use dryRun=true for preview. Use startLine hints for faster matching in large files.
AI agents use apply_diff to create or update resources in OODA Computer Control — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your OODA Computer Control environment.
apply_diff modifies file content through search/replace operations. While the changes are reversible (files can be restored from backups or version control), the tool enables direct modification of file contents. This is Write rather than Destructive because: (1) changes are reversible, (2) validation happens before application, and (3) dryRun mode allows preview.
From the tool's definition Tool description states it performs 'search/replace operations' and 'applying any changes' to files, which are write/modify operations. The atomic nature and validation mechanism prevent destructive mistakes but still constitute reversible modifications.
Documented attack patterns abuse exactly the kind of access apply_diff gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and OODA Computer Control, and nothing reaches the server without passing your rules. This is the rule we recommend for apply_diff:
{
"version": "1",
"default": "deny",
"tools": {
"apply_diff": {
"limits": [
{
"counter": "apply_diff_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}apply_diff 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.
Free to start. No card required.
Apply multiple search/replace operations to a file in a single atomic operation. Validates all blocks before applying any changes. Use dryRun=true for preview. Use startLine hints for faster matching in large files. It is categorised as a Write tool in the OODA Computer Control MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the OODA Computer Control MCP server in PolicyLayer and add a rule for apply_diff: 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 OODA Computer Control. Nothing to install.
apply_diff 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_diff 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_diff. 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_diff is provided by the OODA Computer Control MCP server (mnehmos/mnehmos.ooda.mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from OODA Computer Control, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
Free to start. No card required.
99 OODA Computer Control tools catalogued and risk-classified — across an index of 43,000+ MCP servers.