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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=false, so 'Read-only, no parameters' is largely redundant. However, the description adds genuinely useful behavioral context unavailable elsewhere: the shape of the result (one line per device, plus a `devices` array with named fields), which matters because there is no output schema.

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?

Front-loaded with the core purpose and scope, then usage routing, then return shape. The sentences are dense but each carries distinct information; only the 'Read-only' clause duplicates the annotations.

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 takes on the burden of describing the return value and does so by naming the per-device fields (id, label, category, size_cm, screen_px, screen_aspect, recommended_screenshot_px, variants, browser_and_dock). Nothing an agent needs to call it or consume the result 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?

The tool takes zero parameters and the schema is an empty object, so there is nothing to disambiguate. The description correctly reinforces 'no parameters', which sets the right expectation for the caller.

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 (Lists) and resource (every device model Showoff renders), then enumerates the categories covered (phones, tablets, laptops, displays, browser windows) and the fields returned per device. An agent can distinguish this from sibling list_* tools and from get_scene/create_project without opening a schema.

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 names the downstream tools that consume its output (create_project, edit_scene's add_device/update_device, create_launch_video) and the purpose of the lookup (picking a device id or variant, or advising on screenshot dimensions). This is a clear when-to-use statement with the alternatives named.

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