add_usd_variant_set

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

Annotations already declare readOnlyHint=false, destructiveHint=false and idempotentHint=true, so the safety profile is covered. The description adds useful behavioral detail beyond them: it specifies the operation only creates an empty set and discloses the already_existed return signal, which concretely explains the idempotency semantics.

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?

Front-loaded with the action and resource in the first clause, with the return shape given compactly afterward. Both sentences carry information (action, idempotency behavior, return fields) and there is 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?

For a mutation tool whose annotations already cover safety and idempotency, the description supplies the missing return contract (there is no output schema) and the empty-set creation behavior. The only gap is the absence of routing guidance against sibling USD authoring tools.

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 all four parameters including the position enum values are already documented in the schema. The phrase 'at the requested list position' references the position parameter but adds no meaning beyond what the schema provides, so the baseline 3 applies.

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 and resource ('Author a new (empty) variant set on a prim'), and the 'empty set' qualifier plus the 'variant set' noun distinguish it from the sibling add_usd_variant, which adds a variant to an existing set. Clear, though it does not explicitly name that sibling.

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?

There is no explicit when-to-use or when-not-to-use guidance, and no alternative is named. The agent must infer context from the verb and the surrounding USD sibling tools; nothing routes it between add_usd_variant_set, add_usd_variant, and list_usd_variant_sets.

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