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

Annotations already cover read-only, idempotent, closed-world behavior, so the description only needs to add return-shape context. It does add that the picture itself is attached (and a video yields the poster frame), which is genuinely useful, but says nothing about what happens with an unknown/deleted id or size limits.

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?

A single sentence that front-loads the resource and then the scope and return contents. Dense but not padded; the em-dash aside about id origins is slightly crammed but earns its place.

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 simple read tool with full schema coverage and rich annotations, this is nearly complete: it covers id provenance, return fields and the attached image. Missing only error/missing-id behavior and any mention of the optional user_goal.

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 both required params and the user_goal param are documented in the schema already. The description restates the id provenance but adds no new syntax or constraint detail beyond what the schema says; the optional user_goal is not mentioned at all.

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 pair (fetch one exact brand library item) and names both sources of the id (list_brand_assets for uploads, list_creations for finished creations). It clearly distinguishes itself from the sibling list_brand_assets by being the single-item 'exact' lookup.

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?

Tells the agent to use this to 'check it before showing the user' and points to the sibling list tools as the source of ids. It doesn't explicitly say when not to use it (e.g. versus search_brand_library), but the workflow context is clear.

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