Hidden stems (Cang Gan)

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 contributes the credit cost (10 credits, Tier 1) and the non-obvious interpretive behaviour around storage branches, but says nothing about precision requirements, dependency on time/timezone for correct branch derivation, or output structure.

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?

Three tight sentences, front-loaded with the core resource definition and followed by the most useful domain caveat. The bracketed group/endpoint/required/cost footer is boilerplate but compact and does carry the credit cost.

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 the annotations cover safety. But for a 12-parameter computation tool with 17% schema coverage, an agent still lacks guidance on how time, timezone, dayBoundary and trueSolarTime change the result — a meaningful gap for a chart-derived computation.

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 17% across 12 parameters, and the description adds no meaning for any of them — not the required date, the optional time, gender, dayBoundary, stageSchool, trueSolarTime, or includeFullTable. The note about storage branches describes output semantics, not input semantics, so the description fails to compensate for the schema 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 states precisely what data is returned — the one-to-three stems each branch shelters, with role and weight — which is a concrete and non-trivial ressource definition distinct from sibling BaZi tools (chart, day_master, element_balance). However there is no verb/action framing and no explicit acknowledgement of which sibling to pick instead when the agent wants the full four pillars or the element balance.

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?

No guidance on when to call this versus astroway_bazi_four_pillars, astroway_bazi_element_balance, or astroway_bazi_ten_gods, all of which overlap in subject matter. The only directive is a data-semantics caveat about storage branches, which is not a usage rule.

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