ephemeris_natal_chart

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

The description fully discloses behavioral traits beyond the annotations: it mentions credit cost, automatic inclusion of asteroids, the effect of house_system defaults, and that include_visual costs extra credits. It does not contradict the readOnlyHint and destructiveHint 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?

The description is moderately long but well-organized with separate sections for example, credit cost, and format notes. Every sentence adds value, though it could be slightly more concise. The example is particularly helpful.

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?

Given the complexity (10 parameters, nested objects, no output schema), the description is comprehensive. It explains what the tool returns, credit cost, format options, and future-use parameters. The agent has enough context to use the tool correctly without additional information.

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 100% schema coverage, the description adds significant meaning beyond the schema. It clarifies that include_arabic_parts and include_fixed_stars are reserved for future use, explains the difference between json and llm formats, and provides context for the visual_config nested object. This helps the agent understand parameter behavior effectively.

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 explicitly states the tool calculates a full natal chart, returning planetary positions, house cusps, aspects, and chart patterns. It distinguishes itself from sibling tools like ephemeris_natal_batch and ephemeris_natal_transits by focusing on a single birth chart, making its purpose clear and specific.

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 includes a concrete example with datetime, latitude, longitude, and specifies the credit cost. It also explains the 'llm' format's benefit for token efficiency. However, it does not explicitly state when not to use this tool or compare it to alternatives like the batch or transit tools, though the sibling list implies differentiation.

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