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

Beyond the readOnly/openWorld annotations, the description discloses free-vs-paid result tiers, the Authorization: Bearer tt_… credit billing model, x402 payment without an Apify account, and concrete rate limits (1/IP/UTC day, 20 shared caller pool, 20 global). These are exactly the operational facts an agent needs before calling.

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 and scope constraint are front-loaded, and the sentence-per-idea structure is easy to scan. The payment/credits block is dense but earns its place for a metered tool; only the 'unrestricted monitoring' clause reads as filler.

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?

Auth, billing, rate limits, and single-URL scope are all covered, which is a lot for a one-parameter tool. What's missing is the result shape — whether the resized image comes back as a URL or binary and at what dimensions, since there are no width/height parameters and no output schema.

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% and the sole parameter is already documented as 'One public HTTP(S) URL.' The description's 'one url' phrasing matches the schema without adding syntax, size, or format detail, so the baseline 3 applies.

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 opens with a specific verb and resource ('Resizes one public image') and states the single-input scope. It does not, however, distinguish itself from near-siblings like compress_image, convert_image, or upscale_image, so an agent must infer which image transformation 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?

'Use for one url. Not for batch work or unrestricted monitoring.' gives explicit positive and negative conditions. It stops short of naming the alternative tool for batch or other image operations, which is what would push this to a 5.

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