Solar Return Chart - Annual birthday forecast with relocated chart

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 adds useful behavioral context beyond annotations: the chart is cast for the exact Sun-return moment, returns a full chart, and relocating changes houses and Ascendant. It does not mention rate limits or errors, but these are less critical for a read-only computation with an output schema.

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?

The first two sentences are informative and front-loaded, but the final keyword list ('Solar return chart API, annual horoscope forecast, birthday chart calculator, yearly astrology prediction, relocated solar return') is redundant SEO-style filler that repeats the title rather than adding new guidance. Trimming that list would make the description tighter without losing 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?

For a 9-parameter tool with a full output schema and read-only annotations, the description covers the essential context: what the chart is, when it is cast, what it returns, and its location sensitivity. Less obvious fields like lang, compact, and houseSystem are adequately handled by the input schema, so nothing required to invoke it correctly is missing.

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?

The input schema documents all 9 parameters with 100% coverage, so the baseline is 3. The prose adds meaning beyond the field descriptions by explaining the natal-Sun-return calculation, which ties birthDate, birthTime, and returnYear together, and by emphasizing that latitude/longitude determine the Ascendant and houses. This gives an agent a mental model for choosing location parameters.

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 first sentence names a specific verb and resource ('Generate a solar return chart for any year') and the description enumerates the returned content (planetary positions, house cusps, aspects, Ascendant, Midheaven). This clearly distinguishes it from natal, transit, and lunar return tools, even without naming a sibling.

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?

The description implies usage for annual forecasting ('foundational technique for annual astrological forecasting') and notes location sensitivity, but it never explicitly states when to prefer this over lunar_return, planetary_returns, or transits, nor when not to use it. With 40+ sibling astrology tools, explicit routing would materially help selection.

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