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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false. The description adds value beyond these by stating it is 'Free' and that 'nothing is reserved or started,' which clarifies that no quota is consumed and no side effects occur. This contextualizes the read-only nature with operational implications, exceeding what annotations alone convey.

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 with zero waste. The primary purpose (exact credit cost) is front-loaded, followed by the use case and a critical behavioral note (free, nothing reserved). Every word contributes to agent decision-making.

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 tool with conditional parameters and no output schema, the description covers the essential context: what it does, when to use, and that it is non-committal. It does not detail return structure, but the mention of 'balance and plan eligibility' gives a hint. Given the annotations and schema coverage, the description is sufficiently complete for an agent to invoke it correctly.

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 all five parameters (tool, model, duration, resolution, with_image) are already fully described in the schema. The description does not add any parameter-specific guidance or clarify conditional usage (e.g., duration only for generate_video), so it provides no extra semantic value beyond the schema. Baseline 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 provides the exact credit cost for three specific tool calls (generate_image, edit_image, generate_video) along with the caller's balance and plan eligibility. The verb 'quote' and resource are specific, and it distinguishes itself from executing those calls by saying 'before making it.' It also implicitly differentiates from get_credits by including balance and plan eligibility, not just cost.

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 it whenever price or budget comes up instead of estimating,' which is a clear when-to-use directive. It also notes 'Free; nothing is reserved or started,' indicating it is a non-committal query. However, it does not name alternative tools or explicitly state when not to use it, leaving some inference to the agent.

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