Get YouTube Video Chapters

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

The description adds value beyond the annotations by disclosing the return contents (titles with start/end times) and the edge case behavior (empty list if no chapters). This informs the agent about expected output and failure mode, which annotations don't cover.

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 short sentences, each conveying essential information without redundancy. The description is tightly written and free of fluff.

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 single-parameter read-only tool, the description is complete: it states what it returns, when it might return nothing, and the input format (covered in schema). No critical information 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?

The schema already thoroughly describes the 'video' parameter (ID or full URL) at 100% coverage. The description adds no additional parameter semantics, so a baseline score of 3 is appropriate.

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 'Extract chapter markers and timestamps from a YouTube video,' a specific verb+resource that clearly differentiates this tool from siblings like get_transcript or get_video_info. The additional details about chapter titles and timestamps reinforce the scope.

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 provides clear context: it's for extracting chapters. It implies when to use it (when you need chapter markers) but does not explicitly name alternatives or exclusion criteria. The caveat about videos without chapters adds context.

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