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

Annotations already cover readOnly/idempotent/non-destructive, but the description adds meaningful traits beyond them: no credits are spent, no checkout or approval-page URL is created, shortfall and balance are returned, quoteToken is signed, and film routes fall back to historical_unavailable when prior evidence is absent. It stops short of describing freshness/expiry of the quote token or rate limits.

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 core purpose is correctly front-loaded, but the remainder is a dense run-on chain of statements, including an enumeration of return fields (totalCredits, totalGbpInclVat, balance, shortfall, quoteToken, etc.) that duplicates the existing output schema. Several edge cases are crammed without grouping.

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?

With an output schema and full safety annotations present, the description still supplies the workflow context an agent needs: the operationId link to confirmation, the engineRecommendations selection loop, film pricing routes, and the fact that requested picture changes get separate quotes and no checkout URL is produced. Only quote validity/expiry behavior is missing.

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 already 80% and the two enums (scope, stillQuality) are documented inline, so the schema carries most parameter meaning. The description only adds the relationship that operationId is shared with the confirmation; it adds no format or selection detail for stillShotIds or stillQuality beyond the schema.

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 and resource: it prices the missing storyboard pictures plus the exact video price for one run without charging. That is clearly distinguishable from studio_storyboard_stills_quote and studio_motion_quote, though those siblings are never named explicitly, so the agent must infer the split from context.

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?

Usage is implied rather than stated: the operationId being 'shared by this quote and its confirmation' suggests this precedes studio_generation_confirm, and 'section engine selection returns a revised quote' hints at a re-quote flow. There is no explicit when-to-use, when-not, or named alternative for a picture-only quote.

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