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

Annotations already mark readOnlyHint/idempotentHint true and destructiveHint false. The description adds substantial context beyond that: there is no score, houses and angles are not compared, missing birth times make Moon aspects approximate, and it disclaims event prediction and professional advice. No contradiction with 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 a single dense paragraph, but it front-loads the core behavior and every sentence serves a purpose: use cases, input requirements, limitations, disclaimers, and attribution. It could be lightly restructured for readability, but nothing is wasted.

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?

With both the input schema and output schema present, the description covers everything needed to call the tool correctly: when to use it, what inputs to provide, coordinate lookup, limitations, and required attribution. No critical gap remains.

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 coverage is 100%, so the schema already documents all parameters. The description adds useful meaning by relating person_a/person_b to get_natal_chart's format, requiring decimal-degree coordinates with place-name lookup first, and clarifying that the result is the aspects themselves rather than a score.

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 and resource: 'Compares two birth charts: the major aspects between one person's Sun, Moon, planets and North Node and the other's, each with its orb.' It clearly differentiates from siblings like get_natal_chart and get_transits, and even names those alternatives.

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 explicitly says when to use it: 'Use it when a person asks how two charts relate, which aspects run between two people's charts, or what one person's planet does to another's.' It also provides exclusions and alternatives: 'For one person's chart on its own, use get_natal_chart; for the sky on a date, use get_transits.'

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