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

Annotations already flag readOnlyHint=false, openWorldHint=true and idempotentHint=false, so the mutating, non-repeatable nature is covered. The description adds genuinely new context, namely that credits are debited up to max_credits, which is the key cost consequence of an irreversible call. It does not say whether credits are refunded on failure, but the added value over annotations is real.

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, with the action and cost impact front-loaded before the usage and parameter hints. No redundant or filler wording.

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?

There is no output schema, and the description does not say what a successful call returns (presumably a generation or job id for check_generation), which is the one meaningful gap in a workflow where the result must be polled. Otherwise it covers prerequisites, credit ceiling, and slot semantics adequately for a 5-parameter mutation.

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 coverage is 100%, so every parameter is already documented in the schema. The description reinforces slot value syntax (upload ids, generation ids, default:{n}) and adds that default:{n} applies to official templates, but it largely restates what the schema provides. Baseline 3 applies when the schema does the heavy lifting.

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: 'Starts a video job from a Genjutsu Explore template', plus the credit-debit side effect. It is distinguishable from generate_video because it names the template-driven path, but it does not explicitly contrast with the sibling generate_video or generate_character_sheet.

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?

It gives an explicit precondition: use 'after estimate_cost with matching template_slug and slot inputs', which tells the agent the correct ordering and what must match. It stops short of stating when NOT to use this tool versus the plain generate_video path.

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