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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered. The description usefully adds behavioral context the annotations do not: the return format (plain text plus title, channel, caption languages) and the failure conditions (no captions, private/members-only/age-restricted videos).

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-loaded with the core action, followed by return format and limitations in a compact three-sentence structure. Every sentence earns its place with no redundancy.

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 correctly carries the return-value explanation (plain text with title, channel, caption languages) and also documents the key failure modes. Nothing an agent needs to invoke it correctly is missing.

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 100%, so all three parameters (url, language, timestamps) are fully documented in the schema itself. The description alludes to caption languages but adds no meaning beyond what the schema already provides, so the baseline of 3 applies.

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 (get the transcript of a YouTube video from its link) with clear scope. The YouTube-specificity implicitly differentiates it from siblings like transcribe_tiktok_video, but it never names or references those alternatives 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?

Provides clear exclusion criteria ('Does not work for videos without captions, or for private, members-only or age-restricted videos'), which helps an agent decide feasibility upfront. It does not, however, tell the agent when to prefer a sibling tool such as get_transcription_result instead.

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