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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so the safety profile is covered. The description adds real context by disclosing the method (derived from Kua, standard Pa Kua mapping), which is useful, but says nothing about output shape or assumptions beyond that.

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 tight sentences with the core output front-loaded, plus a group/cost tag. No waste, though it is arguably too terse for a 9-parameter tool.

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 no explanation, and the read-only annotations cover safety. However, for a 9-param tool with low schema coverage and no usage guidance, the definition leaves an agent short of what it needs to choose this over the Kua sibling and to populate non-required params.

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% across 9 parameters, and the description contributes no parameter-level meaning at all. The phrase 'from Kua' weakly implies a birth date and gender are needed, but the many optional params (fields, precision, timezone, timezoneOffset, language) remain unexplained here and largely undocumented in the schema.

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 output (4 lucky + 4 unlucky compass directions) and the derivation basis (Kua / Pa Kua mapping), which is concrete enough to distinguish it from the generic sibling astroway_chinese_feng_shui_kua. It does not explicitly name the sibling it differs from, so it falls short of a 5.

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?

There is no when-to-use guidance, no prerequisites, and no routing to alternatives. With a closely related sibling (astroway_chinese_feng_shui_kua) that yields the underlying Kua number, the omission of any 'use X for the number, this for the directions' guidance is a real gap.

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