Calculate a natal chart

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It goes beyond basic functionality by explaining that results are cross-checked by two independent implementations and that the call FAILS rather than returning a chart on disagreement. It also states the exact-birth-time requirement, giving the agent a clear failure condition.

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 three purposeful sentences: the first defines scope and output, the second explains the fail-safe behavior, and the third gives usage and routing guidance. No sentence is wasted and the critical usage guidance is front-loaded.

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?

Even without an output schema, the description enumerates the full set of returned chart components and the failure behavior when the two astronomy implementations disagree. Combined with fully documented parameters and an explicit alternative tool for missing birth time, an agent has enough context to invoke the tool correctly.

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 description coverage is 100%, so the schema already documents all five parameters in detail. The description adds some contextual meaning by emphasizing the exact birth time requirement, but does not add substantive meaning to any individual parameter beyond what the schema provides.

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 states a specific verb ('Compute') and resource ('full natal/birth chart'), then enumerates exact output elements: ten planets with sign/degree/house/retrograde, ascendant, midheaven, and twelve house cusps. This clearly distinguishes the tool from siblings like verify_ascendant and calculate_chart_without_birth_time.

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 explicitly says 'Use this whenever a user asks for a birth chart, rising sign, or planetary placements' and warns not to do the arithmetic manually. It also provides a clear exclusion and alternative: if birth time is unknown, use calculate_chart_without_birth_time.

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