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

Annotations already cover the safety profile (readOnlyHint=true, idempotentHint=true, destructiveHint=false), so the bar for the description is lower. The description adds valuable behavior beyond annotations: 'No generative AI is used' discloses the computation method, and the scope boundary (no personal birth data) clarifies what kind of calculations are involved. No contradiction with annotations.

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 English portion is three tight sentences: trigger condition, return fields, exclusions, plus a one-sentence behavioral note. Information is front-loaded with the usage condition before the payload list. The bilingual duplication roughly doubles length, but it's purposeful for a Chinese/English almanac tool serving both locales, so it earns its place.

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?

Complete for a read-only lookup tool: an output schema exists so return format needs no prose explanation, both parameters are fully covered by the schema, annotations carry the safety profile, and the description covers when to use, when not to use, and what data scope applies. With only 2 simple parameters and siblings named, nothing an agent needs to call this correctly is missing.

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% — both date (with pattern and format) and locale (with enum and default) are fully documented in structured form. The description adds no parameter detail beyond restating that the tool is for a 'specific calendar date,' which maps to the date param. Per rubric, baseline 3 is correct when schema does the heavy lifting.

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: returns Chinese almanac data for a calendar date. Clearly names the return payload (day pillar, lunar date, activities, directions, zodiac clash) and explicitly differentiates from siblings by stating it does NOT do Bazi charts or daily Bazi guidance. A tool name alone (get_daily_almanac) plus this description tells the agent exactly what this is and is not.

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?

Gives an explicit trigger condition ('when the user asks for Chinese almanac information for a specific calendar date without personal birth data'), and an explicit exclusion ('Do not use this for a personalized Bazi chart or daily Bazi guidance'), implicitly routing the agent to the named siblings. The agent needs no inference to decide tool selection.

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