listSources

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

Annotations already cover the read-only safety profile, yet the description adds substantial behavior: permission-gated labels (microphoneLabelsUnavailable/cameraLabelsUnavailable and the remediation of asking the user), and the exact conditions under which windows are omitted (minimized, hidden, other desktop/Space, behind full-screen). This is meaningful context beyond structured fields.

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?

Purpose is front-loaded in the first sentence, followed by usage and edge cases. It is dense across four sentences but each carries distinct information; only minor tightening is possible.

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?

With no output schema, the description fully explains the shape of the return (display indexes, window titles, device names, and the two unavailability booleans) and the listing exclusions. An agent has everything needed to call it and interpret 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?

The tool takes zero parameters, so per the rubric the baseline is 4. The description usefully explains how the returned values (indexes, title substrings, name substrings) are consumed downstream, though there are no parameters 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?

Specific verb (List) plus concrete resources (displays, windows, microphones, cameras) tied to the OpenScreen product. It implicitly distinguishes itself from siblings like startRecording/stopRecording by framing the output as input to startRecording.

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?

Explicitly routes the agent to the consuming tool ('Pass startRecording a display's index or part of a window's title'), which is clear usage context. It lacks an explicit when-not-to-call statement, but the workflow context is unambiguous.

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