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

With no annotations, the description carries the full burden of behavioral disclosure. It mentions the scope and speed ('instantly') but does not disclose supported unit symbols, handling of temperature offsets, invalid input behavior, rounding, or whether results include units. The schema examples even introduce ambiguous abbreviations like 'gb' and 'mb' that could confuse the agent.

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 a single, front-loaded sentence that efficiently conveys the tool's scope. Every word contributes value with no filler or redundancy.

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?

Although the tool is simple and schema coverage is high, there is no output schema and no annotations. The description fails to provide an explicit supported-unit list, leaving the agent to guess valid unit codes, especially for ambiguous examples like 'gb' and 'mb'. For a conversion tool, this is a significant completeness gap.

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%, so the baseline is 3. The description does add category context for interpreting fromUnit/toUnit, but the schema examples already list representative units. No additional syntax, unit normalizations, or format details are provided beyond the schema.

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 specifies the verb 'convert' and the resource 'major units' across concrete categories (length, weight, temperature, area, capacity). This clearly distinguishes it from sibling converters like color-converter, timestamp-converter, or base64-converter by scoping to physical measurement 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?

No guidance is provided about when to use this tool versus alternative converters, nor any exclusions. The description implies general unit conversion use but does not state when not to use it or which sibling handles other conversion types (e.g., timezone-converter for time zones).

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