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

Annotations already declare read-only, idempotent, non-destructive, closed-world behavior, so the safety profile is covered. The description adds useful non-annotation context: a fixed 10-credit (Tier 1) cost and the Ziping-canon direction method. It says nothing about how many pillars return, timezone handling, or any auth/rate constraints, so it stays at the baseline-plus level.

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 compact sentences with the core concept and direction logic front-loaded, followed by clearly tagged Group/Cost metadata. No filler, though the second sentence is borderline trivia for an agent deciding whether to call the tool.

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?

The existence of an output schema removes the need to describe return values, and cost is disclosed. However, for a 9-parameter tool with 44% schema coverage and no usage guidance, the description leaves gaps an agent must fill via the schema and sibling list.

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?

With 9 parameters and only 44% schema description coverage, the description should carry more of the load. It touches only gender (as a direction input) and says nothing about count, fields, precision, time, timezone, or timezoneOffset, so callers must read the schema for the majority of inputs.

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 verb+resource: the 10-year luck pillar sequence (Da Yun), plus the direction rule (gender + year-stem polarity per Ziping canon). An agent can tell it computes a BaZi period sequence rather than a single pillar. It does not explicitly distinguish itself from sibling tools like astroway_bazi_year_pillar_decade or astroway_bazi_yearly, which prevents a 5.

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?

The description explains how the direction is derived, not when to call this tool versus alternatives. There is no mention of prerequisites, exclusions, or sibling tools such as astroway_bazi_yearly or astroway_bazi_year_pillar_decade, leaving selection entirely to inference.

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