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

Annotations already declare readOnly, idempotent, closed-world behaviour, so the bar is low. The description still adds substantive context by disclosing the nature of the payload — explanations plus the tradition and sources behind them — which tells the agent to expect prose/reference content rather than computed values.

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 tightly written sentences with no filler, and the core purpose is front-loaded before the qualifying examples. Every clause carries information the agent can act on.

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 one-optional-parameter reference tool with no output schema, the description covers what the tool is, what it returns conceptually, and when to reach for it. A brief note on response shape (single prose block vs. per-topic sections) would close the last 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 100% and the schema already enumerates example keys (dayOfficer, solarTerm, lunarDate, dayPillar, moon), so the baseline applies. The description's examples add term-name glosses but no new parameter semantics, and it does not restate the 'omit for all' default behavior in its own text.

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+resource pair: it explains how each almanac value is calculated and what terms mean, with sources. This implicitly separates it from value-returning siblings like get_almanac_day or get_solar_terms, but never names them explicitly.

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 phrase 'Answers how something is computed or what a term means' gives a clear triggering condition, reinforced by three concrete example terms (建除, 节气, 日柱). No exclusion is stated, so an agent must infer that actual almanac output comes from get_almanac_day rather than from this tool.

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