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

Beyond the readOnly/openWorld annotations, it discloses the 30-minute preview lifetime and refresh behavior, the fact that the result carries one picture per page up to 12 in page order with a Morpha-shaped placard, and the instruction never to fetch your own image. It also documents the side effect of the preview appearing in the chat, which annotations alone do not convey.

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 purpose, then usage, then return payload, then constraints, so an agent can stop reading early. It is dense and runs long with several stacked clauses (return shape, picture payload, expiry, controls), so a small amount could be trimmed without loss.

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?

Covers everything needed to invoke correctly: when to call, lifecycle/expiry, alternative rendering path, and the image payload semantics that the output schema likely does not explain. Nothing an agent needs to select or invoke the tool 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 coverage is 100% and the enum is already in the schema, but the description adds real meaning: 'full' is spelled out as play, scrub bar, time, sound and fullscreen, versus 'play' as the play button alone, plus the intent ('a preview that should look like a plain video'). It adds little about projectId beyond the schema's 'Id of the project to show.'

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 ('Show the project in the chat as a live preview') plus the distinguishing behavior: the preview plays and follows every edit, and multi-page projects turn pages. This clearly separates it from open_project/create_project and from render_video, which an agent can tell apart 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?

Gives explicit timing ('call it once per project, right after creating or opening it'), an explicit do-not-call-again rule ('later edits appear in the preview without calling again'), a re-call condition after the 30-minute expiry, and a stated fallback for clients that cannot render ('give the person the editorUrl instead'). This is textbook when/when-not/alternative guidance.

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