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

Annotations only say readOnlyHint=false, idempotent=false, destructive=false; the description adds materially: no credit spend, consumption of a job slot against the plan's concurrent-operation limit, asynchronous immediate return, the exact completion condition (output.render_id match plus output_current true), and the trap that an older URL is not completion. This is exactly the context annotations 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?

Five sentences, each carrying distinct load (purpose, param semantics, cost/slot, async return, completion test), with purpose and the primary parameter rule front-loaded. No filler or repetition of schema types.

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 an async mutation tool with two parameters and an output schema, everything the agent needs is present: how to select videos, that it is non-blocking, the resource cost model, and the precise completion/verification condition. Return-shape details are correctly left to the output schema.

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 0%, so the description must carry parameter meaning, and it does for 'videos': the printed-number naming convention ('Video 1 is 1') and the omit-to-render-all-ready default. 'storyboard_id' is left implicit, which is the only gap.

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 with output ('Assemble a film's derived videos into MP4s'), and immediately contrasts with the sibling get_storyboard, which is named as the polling endpoint. An agent can distinguish this from export_storyboard_video or get_storyboard without opening any 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 says when to omit 'videos' (render every video whose clips are all ready) and describes the post-call polling procedure against get_storyboard. It gives clear positive context but no explicit 'when not to use' or comparison to similar render/export siblings.

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