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

Annotations already declare readOnlyHint=true, idempotentHint=true, openWorldHint=true, and destructiveHint=false, so the safety profile is covered. The description's one addition is cost ("1 credit"), which is genuinely useful billing context not present in annotations, but it says nothing about result volume, pagination limits, or latency.

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 short sentences with zero padding and the purpose front-loaded. However, the brevity crosses into under-specification rather than tightness, since there was room to add routing guidance without bloat.

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 10 parameters, no output schema, and several nuances (engine fallback, date and domain filtering interplay, country vs. language), the description leaves the agent reliant entirely on the schema. It does not explain what a result contains or how credits scale with paging, so it is thin for a tool of this complexity.

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 90%, so nearly every parameter is already documented in the schema, including engine fallback semantics and domain filter formats. The description adds nothing about parameters, which is acceptable at this coverage level but earns only the baseline.

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?

"Search videos" is a clear verb+resource and, because siblings include images, news, scholar, and shopping, the media type alone distinguishes it from most alternatives. It stops short of naming the closest sibling (search) or clarifying that results are video-specific listings.

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 gives no when-to-use or when-not-to-use guidance. An agent must infer from the name alone whether to choose this over search, news, or images, and there is no mention of engine selection tradeoffs (e.g., using auto as a fallback), even though the schema exposes that option.

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