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

Annotations already cover the safety profile (read-only, idempotent, non-destructive, closed-world), so the description's job is to add context — and it does, disclosing the 1900–2100 domain limit and leap-month support, which annotations cannot express. Since there is no output schema, the note that results include can chi for day/month/year plus the solar term is genuinely useful behavioral disclosure.

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?

A single front-loaded sentence: verb, resource, domain limit, and outputs in that order. No filler or repetition of the title.

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 three-parameter, annotation-covered conversion tool with no output schema, the definition supplies the range limit, leap-month caveat, and a sketch of the returned fields. Only the exact shape/format of the returned can chi and solar term data is left unstated, which is a minor gap.

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 67%, with date and leap_month documented inline; the description's phrase 'with leap months, 1900–2100' adds a valid-range constraint on the date parameter that the schema lacks. It does not explain the direction enum values beyond their self-explanatory names, so it stays at baseline-plus rather than adding rich 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 and resource: converts a date between the Gregorian and Vietnamese lunar calendars, with the supported range (1900–2100) and leap-month handling. It is clearly distinct from siblings like get_lunar_day or find_good_days, though it never names an alternative to sharpen the distinction.

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?

Usage is only implied by the stated purpose and the 1900–2100 range constraint. There is no explicit guidance on when to pick this over get_lunar_day or other date-related siblings, and no mention of prerequisites.

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