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

Goes well beyond the annotations, which only declare non-readonly, open-world, idempotent and non-destructive. The description adds the billing contract (credits charged only on success and never more than the quote), the async job/poll pattern via get_ad_job, and the concrete auth requirement (OAuth connect or an 'Authorization: Bearer acd_live_…' header).

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 sentences, front-loaded with what is produced, then prerequisites, then cost and auth. Dense but every clause carries obligations an agent needs; the long parenthetical listing of ad components is the only slight slack.

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 15-parameter, nested-object, async generation tool with an output schema, the description covers the prerequisites (quote_id, avatar/product images), the return handle (job_id), billing behavior and auth. Nothing needed to invoke 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?

Schema coverage is already 100%, so the baseline is 3, but the description adds genuinely non-obvious semantics: quote_id must come from estimate_ad_cost and match these exact fields, and the storyboard-vs-brief precedence rule ('when present it is what renders').

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+resource with full scope: a finished multi-shot video ad with speaking creator, product shots, captions and optional music bed. It also names the two input modes (brief or storyboard) and the image inputs, which separates it from generate_video, generate_ugc_video and write_ad_storyboard.

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 clear workflow context: requires a quote_id from estimate_ad_cost for exactly these fields, and returns a job_id to poll with get_ad_job. It also clarifies that storyboard takes precedence when present and that the brief is optional alongside it. It stops short of explicitly contrasting itself with sibling generators like generate_ugc_video, so no exclusions are stated.

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