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

Annotations already cover the safety profile (readOnlyHint=true, destructiveHint=false, openWorldHint=false), so the description need only add context. 'Looks up each creative ID individually' adds a useful behavioral hint about per-ID resolution, but there is no information on what fields are returned, what happens with invalid/unknown IDs, or response shape.

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?

Two short sentences with the purpose front-loaded and no filler. The second sentence is brief and marginally informative, though slightly redundant with 'by their IDs'.

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-only, single-optional-parameter fetch there is no output schema, so the description's 'detailed information' is vague about what is actually returned. Given the low complexity this is adequate but leaves a meaningful gap about response contents.

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 description coverage is 100%, so the single creative_id parameter is already documented as 'creative id to be query'. The description adds only the notion that lookup is per-ID; it does not clarify format, source of IDs, or handling of the plural 'IDs' wording versus the single integer parameter.

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 gives a specific verb (get/fetch) and resource (detailed information for creative assets), with the lookup key (IDs) stated. It implicitly distinguishes itself from search_library_creatives_by_name by requiring IDs, but never names that sibling, so differentiation is left to inference.

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 phrase 'by their IDs' implies the tool is for when you already hold creative IDs, and 'looks up each creative ID individually' hints at per-item resolution. However, no explicit when-to-use/when-not guidance or named alternative (e.g., search_library_creatives_by_name for name-based discovery) is provided.

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