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

Annotations already cover safety (readOnly, non-destructive, closed-world), so the description's job is to add operational context. It adds the concrete batch limit (1-50), the fact that results carry per-item status (implying partial success/failure), and that signed links are returned — all beyond what annotations declare.

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 compact clause front-loads the operation and the cap, then lists what is returned. Dense and mostly efficient, though the colon-chained phrasing is slightly compressed and the omitted cursor leaves a gap rather than a word to cut.

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?

An output schema exists, so return-shape explanation is not required, and the batch cap and per-item status give useful framing. Still missing for a 2-parameter, zero-coverage schema is any definition of selection_key semantics, invalid-key handling, and the role of cursor.

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 0%, so the description must compensate and it largely does not: it mentions selection_key only as a lookup mechanism without saying what a selection key is or how items missing/invalid are handled, and the 'cursor' parameter is never mentioned at all despite being the only other input.

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 ('Get ... owned creatives'), scoping to owned assets and to a batch-by-key lookup, which separates it from creatives_list. It does not explicitly name the sibling it complements (creatives_get), so differentiation is implied rather than stated.

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 'by selection_key' and 'owned' qualifiers imply the use case (fetching specific known creatives in bulk rather than browsing), and the 1-50 cap implies batching. But there is no explicit when-to-use/when-not guidance versus creatives_get or creatives_list, nor any prerequisites.

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