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

Annotations already declare non-readOnly, non-idempotent, non-destructive, so safety is covered. The description goes further and discloses the non-obvious trait that uploaded photos are identity references and are never shown publicly, which materially affects how an agent should use them. It stops short of covering overwrite/limit-exceeded behavior, hence not a 5.

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 sentences, zero filler, and front-loaded with the action and its limits before the rights and visibility caveats. Every clause carries a constraint or a behavioral fact.

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 3-parameter upload tool with no output schema, the description covers formats, count and size limits, the rights precondition, and the non-public nature of the photos. It omits only peripheral detail such as what happens when a limit is exceeded or how photos are later listed/removed.

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 the baseline is 3, but the description adds meaning the schema lacks: JPEG/PNG/WebP formats, minimum 512 px on the short side, and a 15 MB per-file ceiling. Those constraints are not encoded anywhere in the schema and directly shape how photo_urls should be populated.

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+resource (upload photos of the artist) plus the accepted formats and the cap of 6 per artist. The added note that these are identity references, not public-facing images, lets an agent distinguish this from set_artist_picture without opening either schema.

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 a real precondition ('Only with the rights to use them (rights_confirmed)') and a size/quantity envelope, which implies when this tool is applicable. However it never names alternatives such as set_artist_picture, list_artist_photos or delete_artist_photo, so routing between siblings is left to inference.

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