window_set_frame
Pins a window (by window_id) to fixed bounds {x,y,w,h} in global points, so every take is framed identically across runs. Returns the actual post-constraint bounds. Requires Accessibility permission.
This record as markdown: /tools/com-local-mcp-local-mcp/window-set-frame.md
What window_set_frame does on Local
AI agents invoke window_set_frame to trigger actions in Local. What it does depends on the arguments the agent supplies, and its effects often reach beyond the immediate call: builds kicked off, notifications sent, workflows started.
| Parameter | Type | Required | Description |
|---|---|---|---|
bounds | object | Yes | {x,y,w,h} global points. |
window_id | string | Yes |
Parameters from the server's own tool schema.
Why window_set_frame is rated High
This tool triggers an external operation on the OS window manager — repositioning and resizing a native application window using Accessibility APIs. It is not a simple read, nor does it delete data, but it actively manipulates the system UI state, which classifies it as Execute. Misuse could disrupt user workflows or obscure other windows, warranting medium severity.
From the tool's definition 'Pins a window (by window_id) to fixed bounds {x,y,w,h} in global points' and 'Returns the actual post-constraint bounds. Requires Accessibility permission.'
Risk signalsBulk/mass operation — affects multiple targets
Attacks that exploit this kind of access
The rule that runs window_set_frame safely
PolicyLayer is an MCP gateway: it sits between your AI agents and Local, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For window_set_frame, this is the rule to start with:
window_set_frame stays usable, but rate-capped: a runaway agent can't fire it dozens of times a minute. Everything else on the server is denied unless you say otherwise.
The button opens the PolicyLayer dashboard: create your workspace, connect Local, apply this rule, and every window_set_frame call is checked against it from then on.
Questions about window_set_frame
Pins a window (by window_id) to fixed bounds {x,y,w,h} in global points, so every take is framed identically across runs. Returns the actual post-constraint bounds. Requires Accessibility permission. It is categorised as a Execute tool in the Local MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.
window_set_frame accepts 2 parameters: bounds, window_id. Required: bounds, window_id. The full parameter table on this page comes from the server's own tool schema.
Register the Local MCP server in PolicyLayer and add a rule for window_set_frame: 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 Local. Nothing to install.
window_set_frame is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.
Yes. Add a rate_limit block to the window_set_frame 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 window_set_frame. 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.
window_set_frame is provided by the Local MCP server (local-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
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