video_details

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

With no annotations, the description carries the full burden. It discloses the return format (object with data, error, successful), the default part list, and lists valid parts. This provides meaningful behavioral context beyond a bare 'retrieves details.' It does not mention authentication or rate limits, but the error-handling and defaults are transparent.

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 description is well-structured and front-loaded with the purpose statement. The Args and Returns sections are clear and concise, with no redundant or filler content. Every sentence provides necessary information.

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?

For a simple retrieval tool, the description is complete: it covers parameter semantics, defaults, valid parts, and return structure. It lacks explicit mention of API key or OAuth requirements, but given the output schema exists and the tool is straightforward, this is acceptable. Minor gaps exist in not addressing error scenarios in detail.

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%, but the description thoroughly explains both parameters: id (YouTube video ID, typically 11 characters) and part (comma-separated list with valid values and default). This adds substantial meaning over the bare schema, making the tool usable without consulting external docs.

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 'Retrieves specified information parts... for a YouTube video, identified by its id,' which clearly states the verb (retrieve), the resource (YouTube video details), and the unique identifier (id). This distinguishes it from sibling tools like search_youtube or get_channel_statistics, which serve different purposes.

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: call it when you have a YouTube video ID and need specific resource parts. However, it does not explicitly mention when to prefer this over alternatives, such as search_youtube, or provide exclusions. There is no clear 'when not to use' guidance, so it remains at the implied level.

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