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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description adds two things beyond that: the returned styles include preview cover URLs, and the call is 'Free' — a cost signal that matters next to estimate_cost. It does not mention pagination behavior or that an omitted tool returns the full tool list with options (only implied by 'the tools and their options').

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, front-loaded with the two listing modes, then filtering, then the next-step hand-off. No filler and nothing repeated.

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 five-parameter, zero-required read tool with full schema coverage and a rich annotation set, the description covers both modes, the filter options, the return shape (cover URLs), cost, and the follow-up tool. Only minor gaps remain, such as default page size and the fact that omitting `tool` returns tools plus their options.

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%, so the baseline is 3; the schema already explains tool, limit, offset, search and category in detail. The description only restates the category/search filtering and the tool-scoping idea without adding syntax, defaults, or matching rules beyond the schema.

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 uses a specific verb and resource ('Lists the style-based video tools, or the styles of one tool') and clarifies the two operating modes, including that styles come with preview cover URLs. It implicitly separates itself from list_videos/list_ad_formats by scoping to 'style-based' tools, though it never names an alternative outright.

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 concrete usage context: omit/no tool to enumerate tools, or filter by category or search phrase, and then hand the selected style id to create_video. That downstream hand-off is genuinely useful routing guidance. It stops short of explicit when-not conditions or naming sibling list tools as alternatives.

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