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

Annotations already cover the safety profile (readOnly, openWorld, non-destructive), yet the description adds genuinely new behavior: a credit cost of 1 for transcript plus 1 for summary, and a length-dependent surcharge of roughly 1 credit per additional 45 minutes. It also discloses the public-only scope and the language behavior. It stops short of failure modes such as videos with no captions, so it is strong but not exhaustive.

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?

Two sentences, both front-loaded with the highest-value information: what is returned, then cost and language behavior. The credit-cost clause is dense but every element (base cost, long-video surcharge interval) carries decision-relevant information for the agent, with no filler.

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 no output schema, the description correctly takes on the burden of describing return contents (summary, key points, timestamped notes), and the credit model rounds out the calling contract. What is missing is behavior on failure paths, such as private videos or missing captions, which matters for a tool restricted to public videos.

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%, so the baseline would be 3, but the description adds real meaning beyond the schema: output is written in the transcript's language by default, and translate_to changes which transcript is summarized rather than only the output language. That operational nuance is not evident from the field descriptions alone.

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 names a concrete resource (a public YouTube video) and enumerates the exact artifacts produced: summary, key points, and timestamped study notes built from the transcript. That output profile implicitly separates it from get_transcript, but the description never names a sibling or states the contrast explicitly, so routing still requires the agent to infer.

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 gives an eligibility constraint ('public YouTube video') and clarifies that translate_to selects a different transcript rather than just a different output language, which is useful context. However, there is no explicit when-to-use/when-not guidance versus get_transcript or list_languages, so the agent must reason about alternatives on its own.

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