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

With no annotations provided, the description carries the full behavioral disclosure burden, and it does so well: it states the tool is free and anonymous, stores nothing, returns computed (not AI-generated) data, and that hour-dependent parts are honestly omitted when the birth time is unknown. It does not mention rate limits or error behavior, but the privacy and computation disclosures are substantive for a tool with zero annotation coverage.

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?

The description is front-loaded with the core purpose and is information-dense — every sentence adds value (inputs, scope, privacy, output format, translation expectation, interpretation boundary). It is slightly long for a tool description, but the density justifies the length without obvious waste.

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 12-parameter tool with no output schema and no annotations, the description is commendably complete: it covers input formats with an example, output structure per system, naming conventions, privacy guarantees, and the behavior when birth time is unknown. Minor omissions such as error cases and rate limits prevent a perfect score, but nothing essential to correctly calling the tool is missing.

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 67%, and the description adds meaningful context beyond the schema: it explains that `text` and structured fields are alternatives, ties longitude to the True Solar Time correction, and clarifies that `birthTimeKnown=false` still yields three BaZi pillars. This partially compensates for the schema gaps, though the description does not individually elaborate every parameter.

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 a specific verb (cast) and resource (three destiny chart systems), and enumerates precisely which systems they are — BaZi, Zi Wei Dou Shu, and Western astrology — with meaningful technical qualifiers (True Solar Time correction, tropical zodiac, Placidus houses). It is unmistakably specific about what the tool produces.

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 usage context by defining the two mutually exclusive input modes — a one-line `text` birth description versus structured fields — and instructs the agent to translate Chinese terms for the user and to delegate interpretation. It stops short of explicit when-to-use versus when-not-to-use exclusions, but with no sibling tools listed, differentiation guidance is less critical.

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