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glass_wait_stable

Read-only

Wait for a GUI window to stop changing, then return the settled frame. Restrict settlement to a region, ignore animated areas, or return text-only results for efficiency.

Instructions

Wait until the window stops changing, then return the settled frame. Optional stability_region watches only that sub-rectangle for settling (ignore unrelated motion); optional region crops the returned frame. Set include_image: false for a text-only {settled,width,height} result with no image (region ignored) — cheap before a text glass_diff.

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
ignoreNoWindow-relative rectangles to exclude from the settle comparison. Use for perpetually animating content — a blinking text caret, a clock, a spinner — which otherwise keeps the window from ever settling. Pixels inside a rect never count as changed and never set `saw_motion`. Combines with `stability_region`: rects are always window-relative and are intersected with it. Independent of `region`, which only crops the returned image. A rect that falls partially or entirely outside the compared area — the frame, or the `stability_region` sub-rectangle when one is set — is silently clamped or dropped, masking less than requested or nothing at all; the excluded count is reported as `ignored_pixels`, so a smaller-than-expected value flags a misplaced rect.
regionNoOptional window-relative sub-rectangle for the returned frame.
toleranceNoPer-channel difference (0–255) two frames may have and still count as unchanged (default 0, exact match). Raise it for a backend with dithering or compression noise.
window_idNoCapture/observe this window (id from `glass_list_windows`) instead of the active one, without changing which window subsequent ops target. Omit for the active window.
timeout_msNoGive up after this long (default 5000ms); returns `{settled:false}` rather than erroring.
interval_msNoHow long to wait between capture ticks (default 100ms).
include_imageNoReturn the settled frame as an image (default true). Set false for a text-only `{settled, saw_motion, observed_ms, ignored_pixels, width, height}` result with no WebP — cheap when the next step is a text `glass_diff`. `region` is ignored when false.
settle_framesNoConsecutive unchanged frames required before the UI counts as settled (default 3). Raise it for an app that pauses mid-animation.
stability_regionNoOptional window-relative sub-rectangle to watch for settling; when set, the settle decision ignores changes outside it. Independent of `region`.
Behavior4/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

With readOnlyHint=true, the description adds useful behavioral detail beyond the annotation: it waits for stability, can ignore unrelated motion via stability_region, and can suppress the returned image. It does not contradict the annotations, and it explains the non-destructive observation behavior clearly.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is two sentences with the core behavior front-loaded and no filler. Every clause adds useful information, and the text-mode optimization is included as a practical tip without bloating the description.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness4/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a 9-parameter read-only tool, the description covers the essential behavior, the key parameter interactions, and the text-only result path. There is no output schema, and the description's `{settled,width,height}` shorthand is slightly less complete than the schema's fuller result description, but the schema already carries that detail.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters4/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 100%, so the description does not need to restate parameter details. It adds real value by clarifying the relationship between stability_region, region, and include_image:false, especially that region is ignored when include_image is false.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose4/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description states a clear verb and resource: wait for the window to stop changing, then return the settled frame. It is distinct from sibling tools like glass_wait_for_element or glass_wait_for_region, though it does not explicitly name them or say what they are for.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines4/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description gives clear usage context, including how stability_region narrows settling and when include_image:false is useful ('cheap before a text glass_diff'). It does not provide explicit when-not-to-use guidance or name alternative sibling tools, so it stops short of full routing guidance.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

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