Build Screenshot

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

Annotations already cover safety (readOnlyHint=false, idempotentHint=true, destructiveHint=false, openWorldHint=false), so the burden is lighter. The description still adds real context: it requires an already-booted simulator and documents the return payload shape, which annotations do not convey. It stops short of noting failure modes or overwrite behavior on out_path, so not a full 5.

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?

Three short labeled fragments — action, use-when, returns — with zero filler and the core action front-loaded in the first sentence. Every sentence earns its place.

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 two-parameter read-and-write-artifact tool, the description covers the action, the selection condition against siblings, the precondition (booted simulator), and the return shape. With an output schema present, further return-value detail is unnecessary, so nothing an agent needs is missing.

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?

Schema description coverage is 100%, with both udid (tied to build_list_simulators and an example format) and out_path documented in the schema itself. The description only restates out_path and adds no syntax or format meaning beyond it, so the baseline 3 is correct.

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?

States a specific verb and resource ('Capture a PNG screenshot of the booted simulator') plus the output destination, so the agent knows exactly what this produces. It is clearly distinguishable from screenshot_capture and screenshot_build_all, which are named as the localized-store alternatives.

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 scopes usage to 'an ad-hoc check' and routes localized store screenshots to screenshot_capture / screenshot_build_all. When-to-use and when-to-use-something-else are both stated, leaving nothing to inference.

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