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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so safety is covered. The description adds only the credit cost (10 credits, Tier 1) and the semantic domain; it says nothing about what the response contains or whether time is needed for a month-branch derivation.

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?

Extremely short and front-loaded: the purpose sentence comes first, followed by compact group/cost metadata. Nothing is padded, though the brevity is partly under-specification rather than disciplined concision.

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 an 8-parameter tool with only half the schema documented and no output explanation needed, the description should at least clarify the required date/time inputs and the month-branch dependency. It omits all of that, leaving an agent to infer call requirements from the schema alone.

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 only 50% across 8 parameters, and the description contributes zero parameter detail — it never mentions the required `date`, the optional `time`, or that month-branch determination depends on the solar term boundary. The description does not compensate for the coverage gap.

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 names a specific derived resource — the month-branch animal — and states its interpretive meaning ('inner motivations and private self'), which lets an agent distinguish it conceptually from the year animal. It does not, however, explicitly contrast itself with the close sibling astroway_chinese_zodiac_secret_animal, so it falls short of full sibling differentiation.

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?

There is no guidance on when to call this versus astroway_chinese_zodiac_animal, astroway_chinese_zodiac_secret_animal, or astroway_chinese_zodiac_element. No prerequisites, no context about needing a birth date/time, and no exclusions are stated.

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