AI agents use set_clipboard to create or update resources in Macos Control — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Macos Control environment.
This tool modifies the clipboard state, which is a data modification action. It's categorized as Write rather than Read because it creates/changes data (clipboard contents) with side effects. Severity is medium because while clipboard manipulation is not immediately destructive, it could be misused to inject malicious data into applications that consume clipboard contents, affecting workflows or data integrity.
From the tool's definition Tool description explicitly states 'Write text to the macOS clipboard.' The action is reversible—clipboard contents can be overwritten or cleared.
Documented attack patterns abuse exactly the kind of access set_clipboard gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Macos Control, and nothing reaches the server without passing your rules. This is the rule we recommend for set_clipboard:
{
"version": "1",
"default": "deny",
"tools": {
"set_clipboard": {
"limits": [
{
"counter": "set_clipboard_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}set_clipboard 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.
Write text to the macOS clipboard. It is categorised as a Write tool in the Macos Control MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Macos Control MCP server in PolicyLayer and add a rule for set_clipboard: 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 Macos Control. Nothing to install.
set_clipboard 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 set_clipboard 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 set_clipboard. 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.
set_clipboard is provided by the Macos Control MCP server (peterhdd/macos-control-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Macos 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.
22 Macos Control tools catalogued and risk-classified — across an index of 43,000+ MCP servers.