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

Annotations already set readOnlyHint=true and openWorldHint=true, so the description doesn't need to restate that this is a read-only operation. It adds useful behavioral details beyond annotations: it returns the current status (pending, done with URL, failed), notes that failure is not charged, and provides billing information. This gives the agent a clear picture of what to expect without over-explaining.

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 description is two sentences, front-loaded with the usage condition ('Use this when you started a video with generate_video'), and every piece of information earns its place: the trigger, the return types, the billing info, and the cost. No filler or redundancy.

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?

This is a simple status-check tool. The description covers the key return states and mentions billing behavior. It doesn't explicitly mention the quote parameter, but the schema fully describes it, so the description doesn't need to. Given the absence of an output schema, the description provides sufficient context for an agent to call the tool correctly. Not a 5 because it could have mentioned that a 'done' status includes the video URL, but that is implicitly stated.

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% and both parameters (id, quote) have clear descriptions in the schema. The tool description does not add any new meaning about parameters; it simply refers to 'what was billed' which aligns with the quote parameter but doesn't elaborate. Per the baseline rule for high schema coverage, a score of 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?

The description clearly states the tool's purpose: check whether a video started with generate_video is ready. It identifies the specific resource (video status) and the trigger condition (after starting a video with generate_video), which distinguishes it from sibling tools. It also mentions the types of returns (pending, done with URL, failed) so an agent knows what to expect.

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 description explicitly says 'Use this when you started a video with generate_video,' which is direct usage context. It implicitly tells the agent when not to use it (if you didn't start a video with generate_video) and ties it to the sibling generate_video. The mention of 'Free' also conveys usage cost assumptions.

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