calculate_birth_chart

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

Annotations already establish the tool as read-only, idempotent, and non-destructive. The description adds meaningful behavioral context beyond those hints: it explicitly discloses that no default time is assumed and that Ascendant/house calculations are omitted when birth time is missing.

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 sentences with no filler; the primary purpose is stated first, and the critical uncertainty-handling behavior is placed second. Every sentence earns its place and the structure is easy to parse quickly.

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 output schema and annotations, the description covers the essential call-time behavior and purpose. It could be more complete by explicitly routing to sibling tools for partial results, but nothing critical for invoking the tool 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 schema already describes most parameters. The description adds semantic value by explaining the behavioral consequence of missing birth time, which directly clarifies the purpose of `unknown_time` and `time`. Latitude/longitude and timezone are left to the schema, but their names and ranges are self-explanatory.

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 clearly states a specific action (calculate) and resource (structured natal chart data) from birth information. It does not explicitly distinguish itself from sibling tools like get_planet_positions or get_big_three, but the phrase 'structured natal chart data' conveys a comprehensive scope.

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 gives clear conditional guidance for a common edge case: when birth time is unknown, preserve uncertainty and omit time-dependent results rather than assuming a default. It does not name alternative tools or explicitly say when not to use this tool, but the context provided is actionable.

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