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

With no annotations, the description carries the full behavioral burden. It usefully discloses the output (width and rounded height) and the 16:9 default, plus the free-trial pricing model, but says nothing about error behavior, whether inputs are numbers or strings, or precision/rounding rules.

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?

One front-loaded sentence covers the operation, default, and return shape, followed by a short pricing note. Tight overall, though the marketing emoji adds slight noise.

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 step in to describe return values, which is the key gap it fills. What remains missing is input format guidance given the untyped string parameters and any hint about behavior on invalid input.

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 0% and both parameters are typed only as unconstrained strings, so the description must compensate. It names width and ratio and supplies the default ratio (16:9), which adds real meaning, but does not clarify accepted ratio syntax (e.g., '16:9' vs '1.777') or that width is numeric-as-string.

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: computes height from width and an aspect ratio, defaulting to 16:9, and names the outputs (width, rounded height). However, it does not differentiate from the sibling x402-aspect-ratio, which an agent would reasonably need to disambiguate against.

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?

No when-to-use or when-not-to-use guidance and no alternatives named. The only routing hint is the 16:9 default, which implies a typical case but does not tell the agent how this differs from the sibling x402-aspect-ratio.

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