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

Annotations cover the safety profile (readOnlyHint=false, destructiveHint=false, openWorldHint=false) and the description adds valuable specifics annotations cannot: it is free, takes ~15 seconds, uses no videos now, and leaves the original video intact. However, idempotentHint=false is not addressed (does repeating the same request create another preview script?), and the 'doesn't use any videos' claim is only partly reconciled with the later 'it uses 1 video' statement for the follow-up call.

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?

Long and dense but front-loaded with the selection rule ('Use this whenever...') and organized as scope → behavior → return value → follow-up. The quoted user phrasings earn their place as routing cues; the aside about Paper Collage 2 and video accounting is slightly muddled but still informative.

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 no output schema, the description fully compensates by describing the return payload (new lines with changes marked, other changes, script_id), the latency budget (~15s, up to 25s wait) and the fallback (call get_script). An agent has everything needed to call it, interpret the response and chain correctly.

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%, so both parameters are already documented, and the description largely restates them ('ready videos made with HypeFox's voices' constrains video_id; 'in the user's own words' restates request). The eligibility and formatting constraints add some meaning, but not enough to go far beyond the schema baseline.

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: it modifies a video the user already has, starting from that video and changing only what the request touches. It explicitly contrasts with making a new video from an idea, which separates it from make_video, make_video_from_audio and preview_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?

Names the triggering user phrasings, gives an explicit prohibition ('never make a new video from an idea for that'), states eligibility limits (only ready videos made with HypeFox's voices, not user audio/footage), and prescribes the follow-up flow (show result, then make_video with the returned script_id).

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