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

Annotations already cover the read-only, idempotent, non-destructive profile, and the description adds useful operational context the annotations cannot: expected latency under 1 s, the USD 0.001 price with no free tier, the first-page-only limitation, and a prompt-injection warning about returned text. It stops short of describing failure modes or rate limits.

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 verb and resource, then constraints, then pricing and safety note — every sentence carries information. Minor defects: a stray double period after get_youtube_transcript and a slightly dense run of facts.

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 an output schema present, the description needn't explain return shapes, and it adequately covers scope, cost, latency, and data-trust posture for a two-parameter read tool. Only the missing sibling differentiation for search_youtube_videos keeps it from being fully complete.

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 100% with both parameters documented, including the no-pagination behavior of 'limit', so the description adds essentially nothing beyond what the schema provides. Baseline 3 is appropriate when the schema carries the full parameter burden.

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 ('List YouTube playlist or channel videos') and describes the return content ('video URLs from the first page'). It distinguishes from get_youtube_transcript, but does not differentiate from the sibling search_youtube_videos, and it omits the single-video URL form that the schema accepts.

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?

Gives a clear routing rule ('First page only; captions use get_youtube_transcript') that tells the agent when to pick a sibling instead. It does not, however, mention search_youtube_videos or state when not to use this tool for discovery-style queries.

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