Ten Gods (Shi Shen)

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

Annotations already declare readOnly/idempotent/non-destructive, so the safety profile is covered. The description adds non-annotation context — the POST endpoint and the 10-credit Tier 1 cost — which is genuinely useful for planning, but it never explains how the day master is derived (from date only, or date+time with dayBoundary/trueSolarTime affecting it), which is the key behavioral unknown here.

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?

Purpose is front-loaded and the bracket metadata is compact and scannable. The ten-gods glossary is domain context that overlaps with what the output schema already exposes, so it is mildly redundant rather than essential.

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?

With an output schema present, return values need not be explained, but for an 8-parameter BaZi calculation whose correctness hinges on unstated boundary/solar-time conventions, the description leaves too much for the agent to guess. It is adequate for a naive date-only call and insufficient for anything else.

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 25% across 8 parameters. The description contributes nothing beyond 'date is required'; the consequential options — dayBoundary 23:00 vs midnight (which changes the day pillar and therefore the day master), trueSolarTime, longitude, language — are left entirely undocumented in both schema and description.

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?

States a specific resource and derivation ('Ten Gods classification per day master') and enumerates the five yin/yang pairs, so an agent knows exactly what analytical output to expect. It does not distinguish itself from BaZi siblings such as astroway_bazi_day_master or astroway_bazi_element_balance, which occupy adjacent territory.

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?

Beyond the '[Required: date]' line there is no guidance on when to choose this tool over the many other bazi_* tools, and no prerequisites or exclusions are named. The agent must infer selection purely from the tool name.

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