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 real behavioral context beyond that: it discloses the dual-pillar computation, the disagreement between transmissions, and the specific handling rule that both placements ship and cross-reference each other. It also surfaces a cost tier (10 credits).

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?

Two sentences, front-loaded with the star names and followed by the key methodological caveat, plus compact group/cost metadata. It is reasonably tight, though the second sentence about cross-naming placements is slightly dense.

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 cover safety. However, for an 11-parameter tool at 36% schema coverage, the description leaves a significant parameter gap and gives no usage routing, making it only adequate rather than complete.

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 36% across 11 parameters, so the schema cannot carry the load and the description must compensate. It instead says nothing about date/time format, timezone, precision, fields, stageSchool, trueSolarTime, or includeFullTable, leaving most parameters undocumented in both places.

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 concretely (Peach Blossom, Travelling Horse, Canopy, Heavenly Nobleman, Blade and Void) and states it is 'computed from BOTH the year and the day reference pillar,' so an agent knows this yields Shen Sha symbolic stars. It is distinguishable from BaZi siblings by the star names, though it never explicitly contrasts itself with neighbors like astroway_bazi_four_pillars or astroway_bazi_ten_gods.

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 versus another BaZi tool, and no prerequisites or input context beyond the required date. The only guidance is methodological (why both pillars are used), which explains the output rather than the usage decision.

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