Apply a V4A-format patch to your workspace. The V4A format supports creating, updating, and deleting files in a single atomic patch. Format: * Begin Patch * Update File: src/main.ts @@ context anchor line -removed line +added line kept line * Add File: src/new.ts +line 1 +line 2 * Delete File: sr...
Part of the ArcAgent MCP server.
Free to start. No card required.
AI agents use workspace_apply_patch to create or modify resources in ArcAgent MCP. Write operations carry medium risk because an autonomous agent could trigger bulk unintended modifications. Rate limits prevent a single agent session from making hundreds of changes in rapid succession. Argument validation ensures the agent passes expected values.
Without a policy, an AI agent could call workspace_apply_patch repeatedly, creating or modifying resources faster than any human could review. PolicyLayer's rate limiting ensures write operations happen at a controlled pace, and argument validation catches malformed or unexpected inputs before they reach ArcAgent MCP.
Write tools can modify data. A rate limit prevents runaway bulk operations from AI agents.
{
"version": "1",
"default": "deny",
"tools": {
"workspace_apply_patch": {
"limits": [
{
"counter": "workspace_apply_patch_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}See the full ArcAgent MCP policy for all 45 tools.
These attack patterns abuse exactly the kind of access workspace_apply_patch gives an agent. Each links to the full case and the policy that stops it:
Other write tools across the catalogue. The same approach applies to each: rate-limit and validate the arguments.
Apply a V4A-format patch to your workspace. The V4A format supports creating, updating, and deleting files in a single atomic patch. Format: * Begin Patch * Update File: src/main.ts @@ context anchor line -removed line +added line kept line * Add File: src/new.ts +line 1 +line 2 * Delete File: src/old.ts * End Patch Context lines (prefixed with space) and @@ anchors locate the edit position. No line numbers needed.. It is categorised as a Write tool in the ArcAgent MCP MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the ArcAgent MCP server in PolicyLayer and add a rule for workspace_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 ArcAgent MCP. Nothing to install.
workspace_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 workspace_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 workspace_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.
workspace_apply_patch is provided by the ArcAgent MCP server (araujota/arcagent). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 45 ArcAgent MCP tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
Free to start. No card required.
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