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

Annotations already declare readOnlyHint=true and destructiveHint=false. The description adds valuable non-annotation behavior: the request is metered and may take longer when captions must be resolved. This cost/latency disclosure goes beyond what the schema or annotations provide and helps the agent set expectations, without contradicting the structured fields.

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 sentences, each earning its place: the first states the core action, the second summarizes the return shape, and the third adds a critical latency/cost caveat. The most important information is front-loaded with no filler or repetition of the tool name.

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?

An output schema exists, so return-value details need not be spelled out. The description covers the core action, output summary, and metering behavior. However, it lacks any guidance on how language selection works and does not explicitly route the agent away from sibling tools like get_youtube_channel_transcripts, leaving a noticeable gap for effective tool selection.

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 0%, so the description must carry the burden of explaining parameters. It clarifies video_id as a YouTube video ID but says nothing about the language parameter—its purpose, how 'auto' behaves, or how it relates to the returned 'available caption languages.' With two parameters and only one partially explained, the description fails to compensate for the missing schema descriptions.

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 opens with a specific verb and resource: 'Fetch a normalized transcript for a YouTube video ID.' It names the exact artifact, differentiates from sibling transcript tools that operate at channel or post level, and lists the concrete return types (plain text, timestamped segments, caption languages). No ambiguity remains about what the tool does.

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 description implies usage through its 'Fetch a transcript for a video ID' wording, and the singular 'video' contrasts with sibling get_youtube_channel_transcripts, but it never explicitly states when to choose this tool over alternatives or when not to use it. No exclusions or alternative routing are provided, so usage context must be inferred.

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