List Capturable Windows

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

Beyond the readOnlyHint annotation, the description discloses that it uses ScreenCaptureKit and requires Screen Recording permission, adding meaningful behavioral context. It also explains how to pass windowId to capture_window, giving additional practical transparency. The description does not contradict annotations.

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

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

The description is two sentences, front-loaded with the core action and purpose. It efficiently includes the data fields, the target use case, and a key prerequisite without fluff. Every sentence contributes meaningfully.

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

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

For a parameterless read-only listing tool, the description covers all essential aspects: what it lists, why you'd use it, what data it provides, and the required permission. Even without an output schema, the field list gives sufficient context for expected results.

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

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

With zero parameters and an empty schema, the baseline for this dimension is 4. The description adds value by enumerating the fields that will be returned (windowId, title, frame, owning app details), which helps users understand what they will get even though there are no inputs to document.

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

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

The description clearly states the tool's function: listing on-screen windows available for capture_window. It specifies the data returned (windowId, title, frame, app ownership) and ties it to the capture_window workflow, distinguishing it from generic window listing tools like window_list.

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

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

The description explicitly says the results are for use with capture_window, which implies this is the prerequisite step for window capture. It also mentions the Screen Recording permission requirement, which is a practical prerequisite. It doesn't explicitly exclude alternative uses or compare with sibling tools, but provides sufficient contextual guidance.

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