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

Annotations declare destructiveHint=true, idempotentHint=false and openWorldHint=true, and the description goes well beyond them: it explains subject-centred cropping with centre fallback, down-only scaling (never upscaling), a pre-emptive checkpoint with rollback on failure, and export of a download link. This is exactly the extra context needed for a destructive, non-idempotent tool.

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?

Front-loaded with the core action and outcome, then behaviour, then formats. The format enumeration is long but each entry carries loader-relevant data (dimensions), so it earns its space; the story_reel note is a minor tack-on.

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 no output schema, the description does most of the work on returns, mentioning the download link and the story_reel key-content hint. A little more on the actual response shape or size of the exported file would make it fully self-contained.

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 the 3 baseline applies, but the description adds real meaning the schema lacks: concrete output dimensions per enum value and the note that cinema_wide is crop-only. It also explains the `focus` default logic in prose matching 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 (crop), resource (photo), and purpose (for a platform), plus the distinguishing outcome: a finished JPEG in one call. This separates it from the generic `crop` and `export_photo` siblings without requiring the schema to be opened.

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 heavily implied by the platform format list and the 'in one call' framing, which hints at the multi-step crop/resize/export alternative. However, it never names the direct sibling alternatives (`crop`, `resize`, `export_photo`) or states when NOT to use it.

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