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

Annotations already declare readOnlyHint, idempotentHint, non-destructive and closed-world, so the safety profile is covered. The description adds the solar-term boundary semantics and the cost/group metadata, which is useful context, but says nothing about how missing time or timezone inputs affect the computed pillar.

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 clause carries the core meaning with no filler; the group and cost tags are compact metadata. It is terse rather than padded, though it verges on under-specification.

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?

An output schema exists, so return values need no explanation, but for a 7-parameter tool with partial schema coverage and no usage context, the description leaves the agent without enough to select it confidently among dozens of BaZi siblings.

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 57% and the description contributes zero parameter meaning. The undocumented parameters (date, time, language) include the required one, so the description does not compensate for the gap even though the date/time patterns are somewhat self-explanatory.

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 the specific resource (month stem + branch) and its derivation rule (solar-term boundaries), which is a real distinguishing detail versus a calendar-month calculation. It does not, however, differentiate itself from the many sibling pillar tools (year_pillar, hour_pillar, four_pillars), which share the same phrasing pattern.

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 statement of when to call this tool versus alternatives such as astroway_bazi_four_pillars or astroway_bazi_monthly, and no prerequisite information. The agent must infer usage from the name alone.

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