flow_estimate_cost

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

No annotations are present, so the description carries the full behavioral burden. It does disclose that nothing is generated and that 'model' is ignored for video, but it never says what the estimate actually returns (cost value? currency? units?), whether there is any rate limit, or how the estimate relates to final billing.

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?

The leading sentence is front-loaded and does the most work; the Args block is a compact, scannable enumeration with no filler. Slightly list-like rather than explanatory, but nothing is 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?

For a six-parameter, all-optional tool with no output schema and no annotations, the definition covers inputs reasonably but leaves the return value undefined. An agent knows how to call it but not what it will get back or how to interpret the figure.

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 0%, so the description must compensate, and it largely does: it maps kind, model, count, image_size, duration_seconds and resolution to their meanings and enumerates the accepted values for kind, image_size and resolution. It stops short of stating defaults, units, or that count only applies to images and duration only to video.

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 — 'estimate the cost of a generation' — and adds the critical qualifier '(nothing is generated)', which separates it from the flow_generate_* siblings. It does not name a specific sibling, so it lands at 4 rather than 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?

The phrase 'before running it' implies the usage window (pre-flight check ahead of a generation call), which is useful implicit guidance. There is no explicit when-not, no mention of what to do with the estimate, and no named alternative.

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