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

Annotations (readOnlyHint, openWorldHint, destructiveHint=false) cover the safety profile, so the description's added value is the generative/behavioral context: it produces 1-3 variants, preserves hook type and structure while avoiding copying the competitor, and returns an open_url that hands off to UGCfy AI for rendering with AI actors. It does not clarify whether script text is also returned alongside the URL.

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?

Two sentences, front-loaded with the action and its required input, then the return value. Every clause (sources, variant count, structure preservation, no-copy constraint, open_url handoff) carries information an agent needs; nothing is padding.

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 six-parameter, no-output-schema tool this covers the essential contract: inputs accepted, what is generated, and what is returned. A minor gap remains around whether the scripts themselves are returned in the response or only reachable via the open_url, which matters for an agent deciding how to present results.

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 100%, so the schema already documents product, platform, variants, breakdown_id, reference_video_url, and reference_transcript. The description usefully frames the three reference inputs as interchangeable alternatives, but adds no format, priority, or precedence rules beyond that. Baseline 3 applies when the schema does the heavy lifting.

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 (rewrite/write variants), the resource (a reference ad -> scene-by-scene UGC script variants for a different product), and enumerates the three accepted reference sources. It is clearly distinguishable from siblings like breakdown_ad and write_ugc_script.

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 opening clause establishes the precondition for use (you already have a proven reference ad as a breakdown_id, video link, or text) and names breakdown_ad as the upstream source for breakdown_id. It never explicitly contrasts itself with write_ugc_script or generate_hooks for the no-reference case, so the alternative routing is left implicit.

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