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

Annotations already establish read-only, idempotent, closed-world behavior; the description adds meaningful domain behavior: what a solar/lunar return is and that it can be cast for the birthplace or another location. It still does not explain the returned chart's contents, but safety is covered by 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?

A single front-loaded sentence covers both modes and the location override with no filler. The parenthetical definitions of solar/lunar return earn their 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?

The read-only annotations and rich input schema make invocation clear, but with no output schema the description never says what the returned chart includes or how it is shaped. It is adequate for selecting the tool but leaves return-value expectations vague.

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?

With roughly 80% schema coverage the schema carries most parameter detail, but the description adds conceptual meaning by tying `kind` to solar-year versus lunar-nearest-now and by indicating birthplace versus alternative return location for coordinates. It does not add syntax beyond the schema, so it is not a 5.

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 two concrete modes—solar return for a year and lunar return nearest now—and says a chart is cast, so the resource is specific. It does not explicitly differentiate from siblings such as natal_chart or transits.

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 implies when each kind applies (solar for a selected year, lunar nearest now) but offers no explicit when-to-use/when-not guidance or named alternatives. The agent must infer that this is the returns tool rather than a natal or transit tool.

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