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

Annotations already declare readOnly, idempotent, non-destructive, closed-world behavior, so the safety profile is covered. The description adds genuinely useful context in billing (10 credits, Tier 1) and endpoint/grouping, but says nothing about whether results are cached, what happens with time/timezone inputs, or any other runtime trait.

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 front-load the purpose, followed by a structured metadata block with group, endpoint, required params, and cost. Every element earns its place; nothing is padded.

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?

An output schema exists, so return values need not be described, and annotations cover safety. For a 9-parameter billing tool the description is sufficient to select and invoke, but the absent usage routing and undocumented optional parameters leave it only minimally complete.

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 only 44%, so the description must compensate. It does clarify the two required inputs meaningfully: date is interpreted as a solar year (digit sum) and gender drives the calculation. But seven optional parameters (time, fields, precision, language, timezone, timezoneOffset, solarYear) get no explanation anywhere, leaving a real gap.

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: computes a Personal Kua number from solar-year digit sum plus gender and maps it to East/West group. An agent knows exactly what it produces. It doesn't explicitly differentiate itself from close siblings like bagua or lucky_directions, though the 'Kua' term and 'for direction work' hint at the relationship.

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?

No when-to-use, when-not, or alternative guidance is given. The phrase 'for direction work' implies the output feeds feng shui direction analysis but never names lucky_directions or bagua as the downstream/follow-up tool. Required params and cost are listed as metadata, not usage reasoning.

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