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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description adds one genuinely useful behavioral fact — that it falls back to the client-shared location when no city is supplied — but says nothing about volume, size of a monthly payload, or how timezone affects the returned times.

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 content is front-loaded — what a month returns comes first, use cases second, location fallback last — and every sentence carries information. The middle enumeration is dense but not padded, though it could be tightened slightly.

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?

There is no output schema, and the description compensates by naming the fields each day entry carries and the extra monthly events (new/full moon times, solar term starts, lunar month starts). Combined with the location fallback note, an agent has enough to call this correctly and describe results.

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 description coverage is 100%, so the schema already documents city, month, and timezone, including the 'omit to use the user's location' default. The description's closing location sentence largely restates that default rather than adding format or interaction detail, so baseline 3 applies.

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?

The description states a specific resource and granularity (a month of the Chinese calendar, one entry per day) and enumerates the payload: lunar date, day pillar, day officer, moon phase, moon times, solar terms, lunar month starts. That implicitly separates it from get_almanac_day and get_solar_terms, but it never names a sibling explicitly, so an agent must infer the boundary.

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 'Answers ...' sentence gives four concrete question shapes the tool handles (favorable days, next moon phase, solar term/lunar month starts, Lunar New Year), which is strong positive routing. There are no exclusions or named alternatives, so it stops short of a 5.

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