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

Annotations already declare readOnly/openWorld=false/idempotent/non-destructive, but the description adds information they do not carry: no network access, no stored state, determinism, and concrete operational limits (64 KB input, 1 s per call, 1 MB result). Those limits directly affect how an agent should batch or size calls.

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?

Front-loaded with the core sentence and organized under explicit labels (When / Not for / Side effects / Deterministic / Limits), so it scans fast. The ES/EN duplication roughly doubles the length, which is defensible for a bilingual catalog but is still redundancy against a single-language reader.

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?

An output schema exists, so return shape needn't be explained; annotations cover the safety profile; and the description fills the remaining gaps an agent would care about — accepted input domain, determinism, failure-relevant limits, and the absence of side effects. Nothing material is missing for a single-parameter conversion tool.

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?

Only one parameter with 100% schema description coverage, so the schema already explains that an integer converts to Roman and a string parses back. The description's 'y viceversa' corroborates direction but adds no syntax, casing, or error-handling detail beyond the structured field. Baseline 3 for high schema coverage.

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 and resource plus the exact domain constraint: 'Converts integers 1-3999 to standard Roman numerals and validates/parses Roman numerals (strict subtractive form) back to integers.' The bidirectional scope and the 1-3999 boundary make it unambiguously distinguishable from radix-convert and from generic number tools in the sibling list.

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?

Explicit 'When: a numeric result has to be exact or reproducible instead of estimated' gives the positive selection condition, and 'Not for: converting an integer of any size between bases 2-36 (radix-convert)' names the sibling to use instead. This is the when/when-not/alternative pattern at full strength.

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