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 conversions are restricted to same-category units and specifically mentions the three temperature scales, but it does not explain error handling for incompatible units, rounding/precision behavior, or whether unit matching is case-sensitive. This adds some behavioral context beyond the basic purpose, but not enough for full transparency.

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, front-loaded sentence that immediately states the action and scope. Every word adds value, listing categories without superfluous detail. It is perfectly concise for the purpose.

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, complete parameter schema, and absence of an output schema, the description is quite complete. It covers the core usage and scope, though it does not explicitly describe the return format (e.g., numeric result) or behavior on invalid input. Still, for a unit converter, this is largely inferable, and the category list provides useful context.

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 already provides thorough descriptions for all three parameters (100% coverage), so the baseline is 3. The description's category list reiterates what the schema's examples imply but doesn't add new parameter-level detail. It does reinforce the 'same category' constraint, but this is already in the schema's 'to' field description, so no significant extra value.

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 a specific action ('Convert a value between units') and a well-defined resource (units of the same category) while listing eight concrete measurement categories. This distinguishes it from sibling tools like convert_currency and convert_timezone by explicitly limiting scope to physical/digital units.

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?

It provides explicit context by listing categories and requiring 'same category', which tells the agent when to use this tool. It doesn't explicitly name alternatives (e.g., 'for currency, use convert_currency'), but the category list effectively excludes them, giving clear guidance without needing exclusions.

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