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

No annotations are provided, so the description must carry the behavioral load. 'Reference card' implies a static, read-only lookup, which is useful, but it says nothing about invalid-sign handling or whether the response is a single record. With an output schema present, return-shape disclosure is not required, so this is a moderate gap rather than a severe one.

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?

One short sentence with no filler that front-loads what the tool is and lists the returned fields. Efficient and appropriately sized.

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?

The output schema covers return values, so the description needn't enumerate them beyond the summary already given. However, for a required free-text parameter with zero schema documentation, the missing input format guidance leaves a real gap.

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 0% and the description never explains the 'sign' parameter's expected form (e.g., 'Aries' vs 'aries' vs a date). With a single undocumented required parameter, the description should compensate but does not.

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 resource ('reference card for a zodiac sign') and enumerates the exact fields returned (element, modality, ruling planet), which clearly distinguishes it from siblings like compute_natal_chart and get_current_transits. It lacks an explicit verb but the noun phrase is unambiguous.

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 guidance on when to use this versus compute_natal_chart or get_current_transits, and no note on prerequisites. The lookup nature is only implied by 'reference card'.

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