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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so safety is covered. The description adds value beyond that by disclosing there is no extra export charge and that results are returned even beside unfinished edits, which is real behavioral context.

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?

Effectively two compact sentences that are front-loaded with the core action. The trailing cost/clause sentence is dense and slightly awkward ('results beside unfinished edits', 'No public publishing, render, payment or extra export charge') but nothing is truly wasted.

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, return-format detail is not the description's burden, and annotations cover the safety profile. Scope is described adequately, so an agent has enough to call it correctly, with only sibling differentiation 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?

Only one parameter (projectId) with 100% schema description coverage, so the schema already carries it. The description adds no syntax, format, or constraint detail on projectId, making this the baseline 3 for a fully documented single-param tool.

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: 'Returns signed download links for existing finished Music video or Film results and selected range files.' An agent understands the operation, though it never names or distinguishes itself from nearby siblings like studio_video_status, studio_video_preview, or studio_creative_result, leaving overlap ambiguity.

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?

'No public publishing, render, payment or extra export charge' functions as partial when-not guidance, ruling out publishing/rendering as the tool's role. However, there is no explicit 'use this when' trigger and no routing to an alternative sibling for the cases it excludes, so usage is only implied.

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