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

Annotations already declare readOnlyHint=true, idempotentHint=true, and openWorldHint=false, so the safe, deterministic nature is clear. The description adds 'using exact conversion factors' which reassures precision but doesn't cover return format, rounding, or potential limitations. With annotations covering safety, a 3 is appropriate.

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?

A single, well-structured sentence that front-loads the core purpose with examples and then enumerates categories, followed by a URL. No wasted words.

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?

Given the tool's simplicity (3 optional params, no output schema), the description is nearly complete: it specifies scope, examples, and precision. It could mention that no authentication is needed or that results are immediate, but those are minor. The lack of output schema means the description could clarify return format, but annotations and schema suffice for correct invocation.

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%, and both 'from' and 'to' parameters have enums with all units documented in the schema, while 'value' has range bounds. The description does not add parameter details beyond what the schema already provides. Baseline 3 is correct when schema does the heavy lifting.

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 (Convert) and resource (units) with concrete examples (cm to inches, kg to lbs) and explicitly names the 18 categories including length, weight, torque, flow rate. This clearly distinguishes it from siblings like cooking_converter, height_converter, and number_base_converter.

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 by listing example conversions and the breadth of categories, implying usage for any unit conversion. However, it does not explicitly say when not to use this tool or route to more specialized converters (e.g., cooking_converter for recipes), which leaves some ambiguity given the many sibling converters.

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