Convert units

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

With no annotations, the description carries the full burden. It discloses that units resolve by id or symbol and that conversions are restricted to the same category, which are useful behavioral details. However, it does not describe the return format, error handling, or edge cases like ambiguous units, leaving some gaps.

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 concise, consisting of two sentences that each serve a purpose: the first defines the tool's action, and the second clarifies unit formats and directs to an alternative for currency. There is no redundant or irrelevant information.

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 tool with no output schema and no annotations, the description provides essential information but not full context. It does not describe the return value or how to enumerate available units (e.g., via list_units), and could mention behavior for mismatched categories. Nevertheless, it covers the core conversion use case sufficiently for an agent.

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?

The schema covers 75% of parameters, and the description adds value by explaining how units are specified ('by id or symbol') with examples ('cm' or 'centimeter'). This enriches the meaning of 'from' and 'to' beyond the basic schema descriptions, and the 'same category' phrasing clarifies the optional 'category' parameter.

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 clearly states the tool converts numeric values between units of the same category, with specific verbs and resources. It also distinguishes from the sibling convert_currency by explicitly redirecting currency conversions, making its scope unmistakable.

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 an explicit alternative for currency conversions ('For currency use convert_currency'), which helps with when-to-use guidance. It does not mention list_units for discovering available units, but the context is clear for non-currency conversions.

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