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

Goes well beyond the annotations by naming exact failure modes and their codes (402 plan_required, 402 storage_full, -2 handle collision), the validation thresholds (512 px short side, 15 MB, 256 px after crop, JPEG/PNG/WebP), and the fact that a brief mentioning @handle uses the piece verbatim. That is exactly the pre-call context the non-idempotent, open-world mutation annotation cannot carry.

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-loads the core definition and keeps nearly every sentence actionable (sources, constraints, handle derivation, error codes). It is a single dense block and spends a sentence on scene-setting ('The kit is what a music video is made from besides the artist's photos'), which is helpful framing but slightly padded.

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 9-parameter (1 nested) tool with no output schema, it covers sources, prerequisites, validation and error codes thoroughly enough to call it correctly. It never says what a successful call returns (e.g., the created handle or id), which is the one gap an agent would want filled.

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 baseline is 3, but the description adds genuine meaning: handle is derived from the name with a -2 suffix on collision, crop is for cutting a prop out of a larger photo and must keep at least 256 px, and rights_confirmed is only needed for upload/file_url (not stock_id). It does not clarify description vs. the stock caption default 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?

States a specific verb and resource plus its scope: creating an outfit, place or prop kit piece from an image, link or stock photo, optionally cropped. It also draws the boundary between outfit (artist's) and place/prop (workspace's), which no sibling tool covers, so an agent can place it against add_artist_photos, search_stock and update_kit_piece immediately.

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?

Gives concrete routing rules: an outfit needs artist_id, a place or prop is the workspace's, stock_id comes from search_stock (credited, no rights needed) while an upload/file_url needs rights_confirmed plus an active plan and storage room. It does not explicitly point at update_kit_piece for edits or list_kit for inspection, so alternatives are implied rather than enumerated.

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