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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false. The description adds one useful clarification ('calorie (thermochemical)') but does not disclose behavioral details such as rounding, precision, or handling of edge cases. It does not contradict annotations.

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 with a clear verb and all relevant unit names. No filler, repetition, 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, stateless converter with complete input schema coverage, an output schema, and safety annotations, the description fully covers the essential purpose and unit set. No additional prerequisite, environment, or behavioral context is needed.

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?

Input schema already documents all three parameters with 100% coverage and enums for from/to. The description adds meaningful semantic nuance by specifying that 'calorie' is thermochemical, disambiguating it from other calorie definitions not captured in 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?

Description states a specific action ('Convert between energy units') and enumerates the exact unit set (joule, kilojoule, calorie, kilocalorie, watt-hour, btu), making it clearly distinct from sibling converters for length, temperature, volume, etc.

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 implies its use for energy conversions but does not explicitly state when to choose it over alternatives or mention exclusions. There is no 'use this tool when...' guidance, so usage context is only inferred from the tool name and unit list.

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