co_list_variants

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

Annotations already establish read-only, idempotent, and non-destructive behavior, lowering the bar. The description adds a useful behavioral trait beyond those annotations: extra field groups cost an additional round trip per variant. This is actionable cost information that the agent would not otherwise know.

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?

The description is compact and front-loaded, with each sentence earning its place: what the tool lists, its primary role, supported filters, and the round-trip cost caveat. There is no filler or redundancy.

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 an 11-parameter tool with no output schema, the description covers the core listing/filtering purpose and an important performance tradeoff, while defaults and scope values are already available in the schema. It does not explain response shape or pagination edge cases, but the read-only annotations and conventional list-tool behavior make it sufficient for correct invocation.

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?

The description translates several schema parameters into concrete filter categories: rating to min_rating/max_rating, color tag to color_tags, pick flag to pick, filename to name_contains, extension to extensions, and field groups to fields. This meaningfully compensates for the partial schema description coverage, though limit/offset semantics are only lightly implied by 'pagination'.

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 states a specific verb and resource: list variants, and clarifies what variants are with the parenthetical 'editable instances of images'. It also distinguishes this tool as 'the main way to find images', separating it from sibling list/get tools.

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 clear usage context by positioning this as the primary image-finding tool and advises requesting extra field groups only when needed. It does not explicitly name alternatives or exclusion conditions, so it stops short of full when-to-use/when-not-to-use guidance.

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