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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, closed-world), so the description's job is domain behavior — and it delivers: media positions are 1-based and an auto-launch ad #N maps to media at position N. The 'as of launch time' caveat hints that ordering may change after launch, which is genuinely useful context not present in annotations.

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 tight sentences, the primary payload (single creative + ordered media) front-loaded and the positional semantics following immediately. Nothing is repeated from annotations or schema, and every clause carries information.

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?

With no output schema, the description takes on explaining the return value and does so for the critical media-ordering part, which is the non-obvious aspect of this resource. It stops short of describing other creative fields an agent might expect, but for a one-parameter read getter it is largely sufficient.

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?

There is exactly one parameter ('id', 100% schema coverage) and the schema already documents it as 'Creative id'. The description adds no format, range, or sourcing guidance for the id (e.g., where to obtain it), so baseline 3 applies.

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 names a specific resource and scope — 'One creative with its ordered media list' — which distinguishes it from the sibling list_creatives (multiple) and create_creative/update_creative (mutation). The retrieval verb is only implied by the name rather than stated, so it falls just short of a 5.

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?

Usage is implied by describing the returned shape (single creative plus ordered media), but the description never says when to use this versus list_creatives, nor any prerequisite such as needing a known creative id. No explicit exclusions or alternatives are offered.

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