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

Goes well past the annotations by disclosing that credits are spent, that eligibility is constrained per photo, and that a failed-looking call may already have started so list_photos should be checked before retrying - exactly the non-idempotent recovery guidance annotations can't express. This is consistent with idempotentHint=false and destructiveHint=false.

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?

Three sentences, front-loaded with purpose then constraints then failure recovery; nothing is padding. The phrase 'its prices from get_shoot or list_photos name them' is slightly convoluted and could be plainer.

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 non-idempotent, credit-spending mutation with no output schema, it covers cost, eligibility, and retry safety well. It never says what a successful call returns (a job, a new photo id, or the upscaled photo) or how long it takes, which matters for an agent deciding whether to poll.

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?

With 0% schema description coverage the description carries the full load and does so: size is explained via the larger-than-source and 4x eligibility rule, max_credits is defined as the user-agreed price sourced from get_shoot/list_photos rather than a raw budget, and photo_id is scoped to the user's own photos. Substantially more meaning than the bare 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 ('Upscales one of the user's photos') plus the exact output options (1K, 2K, 4K) and the payment source (credits). It never distinguishes itself from the closest sibling, zoom_in, so an agent must infer which of the two upscaling-ish tools to pick.

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 real usage rules: only sizes larger than the source and at most 4x it are offered, prices come from get_shoot or list_photos, and max_credits must be the price the user agreed to. Missing is any 'use this instead of X' routing against zoom_in or edit, and no prerequisite about how the user grants consent to spend credits.

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