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 genuinely useful operational context beyond that: the group (BaZi Four Pillars) and the cost (10 credits, Tier 1). It does not disclose what input the pillar is computed from or any limits.

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?

It is a single front-loaded fragment with no filler, and the cost/group tags are compact. But it is under-specified rather than concise — the terse form leaves the core routing question unanswered.

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 not be explained, and annotations carry the safety profile. Still, for a tool sitting in a cluster of four ambiguous pillar siblings, the description omits both sibling disambiguation and parameter meaning, which is the minimum needed to invoke it correctly.

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 adds nothing about any of the 7 parameters. Notably the required `date` parameter has only a regex pattern in the schema and no description anywhere, so the agent must guess whether it is a birth date, a reference year, or a calendar date — the one thing this tool's semantics hinge on.

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 resource contents precisely (year stem, branch, animal, element, yin/yang), so an agent knows what data comes back. However, it is a noun fragment with no verb and no differentiation from the many near-identical sibling pillars (astroway_bazi_month_pillar, astroway_bazi_hour_pillar, astroway_bazi_four_pillars, astroway_bazi_day_master). The naming pattern makes the distinction inferable, but the description itself does not make it.

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 when-to-use guidance at all: nothing states when to call this instead of astroway_bazi_four_pillars, astroway_bazi_chart, or astroway_bazi_yearly, all of which overlap heavily. No prerequisites, no mention that a birth date is required.

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