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

Annotations already cover read-only and open-world behavior, yet the description adds real value: results come back in YouTube's own ranking order, a cursor is provided for paging, and the call costs 1 credit. That credit cost and ranking-order behavior are not derivable from annotations or schema.

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 short sentences, front-loaded with the verb+resource and followed by scope, ordering, and cost. Minor redundancy between "Search videos." and the following clause, but nothing is wasted.

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 and 3 parameters, the description covers return shape (videos + Shorts, ranking order, cursor) and cost, which is helpful. Gaps remain on result fields, pagination termination, and the undocumented cache_max_age parameter.

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 only 33%, so the description must carry weight. It does explain the cursor as "for the next page," matching the schema hint, but cache_max_age is undocumented in both places and query gets no format guidance (phrases, operators, locale).

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 and resource ("Search videos") and narrows the scope to "Public YouTube search results for a query: videos and Shorts in YouTube's ranking order." That scope implicitly separates it from youtube_channelVideos and youtube_searchHashtag, though no sibling is named explicitly.

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?

Usage is implied by "for a query" and "Public" (i.e., keyword search over public content), but the description never says when to prefer this over youtube_searchHashtag, youtube_searchTypeahead, or youtube_channelVideos. No exclusions or prerequisites are stated.

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