eng_format

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

Without annotations, the description carries the burden of behavioral disclosure. It explains the formatting rule via example ('value=12345 → "12.345k"'), but does not mention edge cases (zero, negative, very large) or whether the output is a string. It is adequate for a simple formatting tool but lacks depth.

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 three short sentences, each serving a purpose: the first states the tool's function, the second gives usage guidance, and the third provides a concrete example. It is front-loaded with the action verb and example, making it highly scannable.

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 (one parameter, no nested objects) and the presence of an output schema, the description is nearly complete. It explains the purpose, parameter, and example, covering all necessary aspects. It does not describe the return format in detail, but the output schema presumably covers this, per the rubric.

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 only defines 'value' as a number with 0% description, so the description must compensate. The description does so by stating 'Params: value' and giving an example that illustrates the parameter's meaning: the real number to be formatted. This fully explains the parameter's role for this simple case.

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 the tool's function: 'show a real number in engineering form (significand + SI symbol)'. It uses a specific verb ('show') and resource ('real number'), which distinguishes it from sibling tools like 'solve_polynomial' or 'base_convert'. It also explicitly points to 'evaluate eng_symbols' as a preferred alternative for expression results, reinforcing its specific scope.

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 explicitly states 'When: show a real number in engineering form', providing clear context for appropriate use. It also gives an exclusion: 'Prefer evaluate eng_symbols for expression results', telling the agent when not to use this tool. This direct alternative guidance is exactly what usage guidelines should offer.

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