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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false, and openWorldHint=false, so the safety profile is covered. The description adds useful non-schema behavior: exact-factor conversion for 140+ units, temperature offset handling, the 'to=all' mode, and the $0.003 USDC x402 price.

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 front-loaded with the core purpose and then adds scope, special cases, and pricing in a compact paragraph. The first sentence largely repeats the title, but overall it is efficient and easy to scan.

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?

The tool has three required parameters, low schema coverage, and no output schema, so the description should carry more weight. It covers dimensions, special temperature handling, and the 'to=all' mode, but it omits return-shape details and does not clarify how unit strings are formatted or how invalid units are handled.

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 only 33%: only the 'to' parameter is documented in the schema. The description partially compensates by listing supported dimensions, unit families, temperature offset units, and 'to=all' behavior, but it does not explain accepted string formats for 'from' or what 'value' represents beyond being numeric.

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 states a specific verb and resource: 'Convert between units' and enumerates 12 supported dimensions. It is clear what the tool does, but it does not distinguish itself from siblings like time_convert, currency_convert, or evm_units, which also handle unit-like conversions.

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 explains how to use the 'to=all' option but gives no guidance on when to use this tool versus alternatives such as time_convert or currency_convert. An agent must infer tool selection from the name and dimension list alone.

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