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

Beyond the read-only and idempotent annotations, the description discloses pricing, latency, failure-charging behavior, caption-only scope, and a prompt-injection caution. These are exactly the operational traits an agent needs before invoking the tool.

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?

The purpose is front-loaded and most sentences carry useful operational information. There is minor noise, such as the unrelated 'on-chain strings' warning and a double period, but the description remains appropriately compact for a paid utility tool.

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?

The tool has rich annotations, a full input schema, and an output schema; the description still adds cost, latency, failure behavior, and security guidance. Nothing critical for correct invocation appears to be 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 the schema already explains url, chapters, and language semantics. The description reinforces the public-caption constraint and optional chapters, but adds little parameter-level detail beyond what the schema provides.

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 uses a specific verb and resource: 'Get YouTube captions and video metadata.' It adds a useful scope limit with 'Public captions only; no media download,' which helps distinguish it from media-download or transcription tools, though it does not explicitly name sibling alternatives such as transcribe_audio or search_youtube_videos.

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?

It states an important usage boundary, 'Public captions only; no media download,' implying when the tool is inappropriate. However, it does not explicitly say when to use this versus sibling tools like transcribe_audio, search_youtube_videos, or list_youtube_videos.

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