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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is covered. The description adds the behavioral detail that it computes both a simplified ratio and a decimal ratio, going beyond the static annotations. No contradiction exists.

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 description is two sentences long, front-loads the core function in the first sentence, and adds relevant usage context in the second. Every word earns its place with no redundancy or unnecessary detail.

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 simple calculator tool with an output schema (indicated by 'Has output schema: true'), the description fully covers purpose and usage context. Annotations and schema handle safety and parameter constraints, so nothing important is missing.

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 description coverage is 100%, with both width and height having clear descriptions (e.g., 'Width in any unit' and 'Height in same unit as width'). The description itself adds little beyond the schema, only referring to a 'pair,' which is already evident from the schema's required fields. This meets the baseline for high schema coverage.

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 uses a specific verb ('Compute') and resource ('width × height pair'), clearly distinguishing this tool from the many sibling calculator tools. It also specifies the two outputs (simplified ratio and decimal ratio), leaving no ambiguity about its purpose.

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?

The description provides clear context for when to use the tool ('image, video, screen, and design contexts') but does not explicitly mention when not to use it or name alternative tools. It lacks exclusions but is still useful for selecting the tool in relevant scenarios.

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