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

Annotations already declare readOnly/idempotent/non-destructive, but the description adds real value beyond them: links are private and signed, a repeat read refreshes expired links, the original source is retained, and no processing or charge is repeated. The charge/re-processing note in particular is behavior an agent needs before re-calling.

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?

Front-loaded with purpose and packed into a few tight clauses; nothing is redundant filler. The signing/refresh/charge notes each carry distinct information, though the run-on structure is slightly dense.

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 an output schema present the description does not need to explain return values, and it still sketches the payload shape. Annotations cover the safety profile and the description covers link expiry and billing behavior, so the definition is complete enough; only explicit sibling routing is missing.

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 both projectId and operationId are already documented in the schema. The description only restates that the result is addressed 'by operationId' and adds no format, scoping, or ownership semantics beyond it, so the baseline of 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 states a specific verb and resource: it returns an owned, completed creative result keyed by operationId, and enumerates the payload (image.url/video.url, downloadUrl, gallery-widget data). This is clearly distinct from status/quote tools, but it never explicitly differentiates itself from close siblings like studio_image_result or studio_motion_result, leaving the agent to infer which result tool to pick.

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?

There is an implicit usage cue ('another read refreshes expired links'), which tells the agent it is safe to re-call when links stale. However, there is no explicit when-to-use/when-not guidance and no named alternative among the many sibling result/status tools, so the agent must infer the routing itself.

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