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

Annotations already cover read-only/idempotent/non-destructive, and the description still adds substantial behavior: the 30-second card granularity, stableShotId presence, a signed stillUrl that expires in about a day, null when no picture exists, and an interactive preview only on supported hosts. Expiry and null-handling semantics are exactly the kind of context structured fields cannot 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?

Four tight sentences, front-loaded with what is returned and followed by the output details that matter (ids, signed URL lifetime, null case) and the cost/safety note. No filler or redundancy.

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 an output schema present the description could have stopped at the summary, yet it explains the practical return contract (URL expiry, null stills, host-dependent preview) and the free/read-only nature. Nothing an agent needs to call it correctly 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?

There is a single required parameter with 100% schema description coverage ('Project id from the Brix36 library'), so the schema fully documents it. The description adds nothing about the parameter, making the baseline 3 appropriate.

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 (returns the stored storyboard) plus its exact output shape: 30-second section cards with lines and numbered shots. An agent can tell this apart from sibling read tools like studio_storyboard_readiness or studio_storyboard_context by the described return structure, though no sibling is named explicitly.

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 never says when to reach for this tool versus the many other storyboard tools (studio_storyboard_context, studio_storyboard_readiness, studio_video_preview). 'Free and read-only' is a faint cost/safety cue but not real usage guidance, and no exclusions or prerequisites are stated.

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