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

Goes well beyond the single readOnlyHint annotation: states it costs no credits, that defaults come from the latest Library items, that the output is a link whose edit is laid out in the browser and is editable and exportable as MP4. The readOnlyHint=true is consistent with the claim that the server only answers a link and the studio does the work, so no contradiction.

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?

Front-loads the key facts (free, no credits, what it does, what it returns) before the style list, so the agent gets the essentials first. The style parentheticals are long and slightly chatty ('like a TikTok edit'), but each earns its place by disambiguating the enum values.

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 carries the return-value burden and does so: it explains the tool answers a link, that the studio reads beats in-browser and opens an editable timeline, and that the result exports as MP4. Defaults for clips, count, and song are all covered.

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 baseline is 3, but the description adds real meaning: 'clips' order and the fact that ids override the latest-items default, 'song' as Storage name or id, and a behavioral characterization of each style value (aura, phonk, villain, velocity) that the schema only labels as 'The edit style.' That materially improves style selection.

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 concrete verb and resource: cutting the person's clips and pictures on a song's beats in a chosen style, returning an editable timeline link. This is clearly distinguishable from siblings like generate_video or edit_flow, which do not do beat-synced montage. The style enumeration further pins down what the tool produces.

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 context for use (beat-synced TikTok-style edit, free/no credits) and states the input conditions: latest Library clips unless creation ids are given, song from Storage by name, 120 BPM grid fallback. It stops short of explicitly saying when to prefer it over edit_flow or generate_video, so it lacks exclusion guidance.

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