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

Annotations already declare readOnlyHint=true, so safety is covered. The description adds real behavioral context by disclosing that API keys are redacted and naming the configuration groups returned (resolutions, DRM, referrer rules, transcribing, watermark), which an agent cannot get from annotations or the minimal schema.

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?

One front-loaded sentence carries the purpose and the most decision-relevant fact (redaction), followed by a short endpoint reference. Dense and mostly waste-free, though the raw API route is marginal for an agent.

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 usefully enumerates what comes back and flags the redaction caveat, which is exactly the gap structured fields leave. Only minor omissions remain, such as error behavior for an invalid or unauthorized library_id.

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 100% with a single well-documented library_id, so the schema carries parameter semantics. The description adds nothing beyond identifying which library is fetched, which is the correct baseline for full coverage.

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 (Fetch) and a precisely scoped resource (one Stream video library), with the returned configuration enumerated. The word 'one' plus the sibling bunny_list_video_libraries makes the singular/plural distinction clear without opening either schema.

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 phrase 'Fetch one ... library' implies retrieval of a single known ID, which implicitly separates it from the list tool, but no alternative or condition is named explicitly. Usage is inferable rather than stated.

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