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

With no annotations, the description carries the full burden; it does disclose the returned content (stars per palace plus pattern labels), implying a pure read-only computation with no side effects. It says nothing about what happens with invalid sittings, whether 'kind' changes the algorithm's behavior, or whether errors are raised versus defaulted — gaps that matter for a chained computation tool.

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 dense sentences with the output contract front-loaded and the input branching compressed into one clause; nothing is redundant. The second sentence is terse to the point of being slightly elliptical, but it earns its place.

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?

There is no output schema, and the description does sketch the return (nine palaces, pattern labels), which is sufficient for an agent to know what it gets back. However, with a jargon-heavy domain and an unexplained 'kind' parameter, an agent lacks enough to be confident it is invoking the right variant or understanding the result labels.

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 coverage is 75%, so the baseline is 3. The description reinforces the yun/date fallback relationship, but it adds nothing about the only wholly undocumented parameter, 'kind' (xiagua/tigua), whose enum values are unexplained in both schema and description.

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 domain resource (Xuan Kong flying star natal chart) and previews its output shape (nine palaces with mountain/facing/period stars plus classical pattern labels), which an agent can distinguish from siblings like yun_period or kua_number. It lacks an explicit verb ('compute'/'return'), so the action is implied rather than stated.

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 clause 'Period from a construction date, or explicit yun' gives a usable rule for choosing between the two period inputs, which is real guidance. However, there is no when-to-use/when-not guidance relative to siblings such as yun_period (which presumably computes a period alone) or form_analysis, and no prerequisites are stated.

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