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

Annotations cover the safety profile (readOnlyHint=false, idempotentHint=true, openWorldHint=true), and the description adds genuinely new behavioral context: credits are charged only on success, a retry with the same quote_id returns the same job, the quote is verified against the card, and full auth requirements (OAuth via host prompt or API key header with signup URL) are disclosed.

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?

Purpose is front-loaded in the first clause, and subsequent sentences each carry distinct payloads (prerequisite, billing semantics, idempotency, auth). It is dense and a little long, and the quote_id derivation is restated from the schema, but nothing is wasted filler.

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 values need not be explained, and for a paid, authenticated mutation the description covers the missing pieces an agent would otherwise guess at: prerequisite quote flow, cost-on-success behavior, retry idempotency, and exact sign-in options.

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 each parameter is already documented in the schema. The description reinforces the quote_id dependency (quantity 1, card duration/resolution) but adds no syntax or format detail beyond the schema's own text; baseline 3 is appropriate.

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 (render/run) and resource (a generation card), and explains the outcome mechanism: the card's prompt and model become a video or image job whose result lands back in the card. This clearly separates it from siblings like generate_image/generate_video (which create new jobs) and add_generation_card (which only adds a card).

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?

Gives an explicit prerequisite workflow: a quote_id must first come from estimate_credit_cost for the card's model and kind, quoted with the card's duration and resolution. It does not, however, state when-not to use this tool or name an alternative for cases like creating a brand-new generation.

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