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

Annotations already declare readOnlyHint, idempotentHint, and openWorldHint, so safety is covered. The description adds genuine behavioral context beyond them: bidirectional conversion, supported notation formats, and a precision claim (digit-exact even at 10⁻³⁰⁰).

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?

Short and front-loaded with an illustrative example before the functional statement, then a reference URL. Every element is relevant, though leading with the example rather than the purpose is slightly unconventional.

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 two-parameter read-only converter with full schema coverage and annotations, the description is sufficient: it covers directions, formats, and precision, and the example implicitly shows the output shape. Nothing critical for correct invocation is missing.

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 schema already documents both 'number' (accepted formats) and 'sig' (mantissa rounding), making 3 the baseline. The description's example value reinforces what 'number' expects but adds no new syntax or semantics.

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?

States a specific verb (Convert) and resource (numbers between scientific, E-, engineering, and standard form) with a concrete worked example (299,792,458 → 2.99792458 × 10⁸). The purpose is unambiguous, though it does not distinguish itself from nearby siblings like significant_figures_calculator or scientific_calculator.

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 never says when to choose this tool over alternatives such as scientific_calculator, significant_figures_calculator, or number_base_converter, nor does it state any exclusions. Usage is only implied by the verb 'Convert'.

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