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 goes further by disclosing the full set of returned data categories, including branch relationships and element variants, and does not contradict the annotations.

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, front-loaded sentences with no filler. The first sentence delivers the core action and return contents; the second states the intended use cases. Every clause earns its place and nothing repeats the structured schema information.

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?

Even without an output schema, the description enumerates essentially all semantic return categories, which is enough for an agent to understand what it will receive. Minor gaps remain around exact response field names or edge-case behavior, but those are not required for selection or correct invocation given the fully documented parameters.

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%, and every parameter (id, lang, compact) already has a detailed description, enum, default, or example in the schema. The tool description adds no parameter-level meaning beyond what the schema provides, so it meets the baseline.

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, 'Retrieve the complete profile of one Chinese zodiac animal,' then enumerates exactly what the profile contains. The singular 'one' distinguishes it from the plural-list sibling get_chinese_astrology_zodiac_animals and the dedicated compatibility endpoint.

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?

It states the intended contexts ('Built for sign detail pages and compatibility features') and the singular scope, which makes the main alternative clear implicitly. However, it never explicitly warns against using it for pair compatibility or the full zodiac list, so the guidance is clear but not exhaustive.

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