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

Annotations already declare readOnlyHint=true, idempotentHint=true and openWorldHint=false, so the safety profile is covered structurally. The description adds only the 1–3999 domain limit (already in the schema bounds) and the note that 'each symbol is explained', which hints at output richness but is not elaborated. No output schema exists, so return shape remains thin.

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?

Two sentences plus a URL, with a concrete example leading to make the domain instantly recognizable. Efficient and front-loaded, though the leading examples delay the actual capability statement by one clause.

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 trivial two-way converter with 3 optional, defaulted parameters and full schema coverage, the description supplies domain, directionality and range. The only real gap is the response shape ('with each symbol explained' is vague), which matters slightly more because no output schema exists.

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 coverage is 100%, so the baseline is 3, but the schema's own parameter descriptions are near-useless ('Convert', 'Roman numeral', 'Number'). The description compensates by mapping the two directions to the toRoman/toNumber modes and restating the valid numeric range, which is genuinely additive.

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 bidirectional operation (number → Roman numeral and Roman numeral → number) and names the exact domain, with worked examples ('MCMXCIX is 1999 and 2026 is MMXXVI'). An agent can immediately distinguish this from neighbors like number_base_converter, number_to_words_converter, or scientific_notation_converter.

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 the two usage directions (encode a number, decode a numeral) and bounds the input to 1–3999, but it never states when to pick this tool over sibling converters or any prerequisites/exclusions. Usage is inferable from the mode enum rather than spelled out.

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