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

Goes well beyond the annotations: discloses that credits are spent at the same rate as the website, that approval_required halts execution and nothing runs or charges until answered, that output is saved to the library, and that under-18 or public-figure requests are refused before any charge. These are exactly the side effects an agent needs for a non-destructive-but-charging write 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?

Purpose and capability set are front-loaded in the first sentence, with cost, approval and refusal semantics following. The prose is dense but nearly every clause carries information; the long aspect-ratio enumeration is slightly redundant with the schema enum.

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 covers the two return behaviors that matter (approval_required vs. saved-to-library) and discloses the billing and refusal rules. It does not describe the successful job payload (job id, status, polling via get_job), leaving a small gap for a charging async tool.

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 baseline is 3; the description adds real meaning on top by explaining reference 'use' as keep-subject vs borrow-style, tying aspect ratios to concrete outputs (Instagram post, story, thumbnail), and noting resolution affects cost. It omits any guidance on approval_id/idempotency_key, though the schema documents those thoroughly.

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?

Opens with a specific verb+resource ('Make an AI image from a prompt') and enumerates the capabilities that distinguish it: styles, reference matching, saved characters, aspect ratios, resolution tiers. An agent can tell this apart from edit_image or create_video without opening the schema.

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?

Gives concrete use conditions (references for keeping a product/person, @tag for a saved character, approval flow when a person must decide) and points to quote_job as the free pricing alternative. It does not explicitly exclude edit_image for modifying an existing picture, so the when-not side is implied rather than stated.

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