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

Beyond the annotations, the description discloses that YouTube results are plan-gated ('on plans with web footage'), that results are relevance-ranked by how well each clip shows the query, and what each result carries (length, license, download link usable by download_media). It does not contradict readOnlyHint=false or openWorldHint=true, and the open-world nature is consistent with querying external libraries.

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 tight sentences: what it returns first, sources second, result shape and scope last. No restatement of the title and no filler.

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 usefully sketches the result fields and the license/plan caveats. It stops short of covering empty results, the default/maximum result count, or pagination behavior, which an agent might need before calling.

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 80%, so the schema already carries the parameter documentation; the description only adds that ranking is by query relevance. The one undocumented parameter (orientation) is left unexplained in both schema and description.

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?

The description states a specific verb and resource ('Video footage for a shot') and names the concrete sources it searches (Pexels, Pixabay, Internet Archive, Wikimedia Commons, YouTube), plus the ranking basis. It also sharply distinguishes itself from photo-oriented siblings with 'Video only; it finds no photos.'

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 scope exclusion ('Video only; it finds no photos') is a genuine when-not signal, and the mention of download_media hints at the follow-up step. But there is no explicit routing against the obvious alternative (generate_video for generating rather than finding footage) or guidance about when stock vs. archive vs. web sources apply.

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