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

Annotations already declare readOnlyHint=true, idempotentHint=true and destructiveHint=false, so the safety profile is covered. The description adds that the two key inputs are not defaulted, which is useful, but discloses nothing about rate limits, auth, or computation behavior. Adequate but not rich beyond the annotations.

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 what the tool produces and then how to feed it. Every clause earns its place; no filler.

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?

For a 10-parameter tool with 0 required fields and an output schema present, the description covers the two decisive inputs and notes they are mandatory in practice. It omits the role of year and language, but since the output schema covers return values and three params carry their own schema descriptions, the remaining gap is minor.

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 only 30% schema description coverage, the description compensates well by reconciling the input alternatives: facing vs facingMountain (degrees or 24 mountains) and period vs occupiedDate (direct period or occupation date). It leaves year, language and occupiedTime unexplained, but it adds real meaning over the raw schema for the critical parameters.

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 a specific resource and its contents: 'the nine-palace natal chart of a building: mountain star, period star and facing star per sector, the named arrangement... and the special patterns.' This distinguishes it clearly from siblings like astroway_chinese_feng_shui_annual_stars or _kua, which cover different Feng Shui computations.

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?

It gives clear input guidance ('Send the facing in degrees or as one of the 24 mountains, and the period directly or as the date the building was occupied') and warns 'Neither is defaulted,' which is essential since no parameter is formally required. It does not, however, name an alternative tool or state exclusions versus sibling tools, so it falls short of a full 5.

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