get_watch_url

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

With no annotations, the description carries the burden of disclosing behavior. It states it returns a URL and optionally includes a start time, but it does not clarify the exact URL format, whether video_id is validated, or how start_time is encoded. No contradictory claims are present.

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 compact and front-loaded with a clear one-sentence purpose followed by an Args list. Every line provides necessary information, with no filler or 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?

For a simple utility with two parameters and no output schema, the description covers the primary purpose and both parameters adequately. It does not detail the return type or URL structure, but this is not critical given the tool's simplicity. The lack of sibling differentiation is a minor completeness gap.

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 0%, so the description must compensate. It does so by explaining video_id as 'The YouTube video ID' and start_time as 'The start time in seconds', adding units and meaning beyond the bare parameter names. However, it does not specify constraints like non-negative start_time or how the time appears in the URL.

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 ('Returns') and resource ('YouTube watch URL'), clearly distinguishing it from sibling tools like get_thumbnail_url and get_normalized_url. It also mentions the optional start_time parameter, making the tool's purpose unambiguous.

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 when a watch URL is needed and mentions the optional start time, but it does not explicitly state when to use this tool versus alternatives or provide any exclusion criteria. The presence of sibling tools (thumbnail/normalized) makes the lack of comparison a minor gap.

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