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

Annotations already declare readOnlyHint true and destructiveHint false, so the safety profile is covered. The description adds meaningful behavioral context beyond those hints: the year follows Li Chun rather than Lunar New Year, and the changeover date is returned in the response. These are exactly the kind of non-obvious behaviors that help an agent call the API correctly.

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 sentences, each earning its place: the first states the result, the second explains scope and usage, and the third clarifies the critical calendar boundary. It is front-loaded, specific, and free of 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?

With no output schema, the description carries responsibility for explaining what comes back, and it does: the nine-star placement per palace, meanings, element strengthen/drain effects, and the changeover date. It is nearly complete, though a tiny gap remains about whether the response includes any house/direction labels or formatting details.

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 100%, so the input schema already fully documents year, lang, and compact. The description reinforces that the year is a solar year and references Li Chun, but it does not add parameter-level detail beyond what the schema provides. Baseline 3 is appropriate.

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 opens with a specific verb and resource: 'Return the annual flying star plate for a solar year' and enumerates exactly what the result contains (star per palace, meaning, element effects). It also distinguishes the annual plate as universal and building-independent, which sets it apart from building-dependent feng shui tools.

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 gives clear context: because the plate is universal, it is 'the layer every yearly feng shui guide is built on.' It also warns about the Li Chun changeover and notes the exact date is returned so callers apply it on the right day. It does not explicitly name alternative tools or state when not to use it, so it stops short of a 5.

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