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

Annotations already declare readOnly/idempotent/non-destructive, so the safety profile is covered. The description adds one genuine behavioral fact — that the result contains both nearby and full milestone lists — plus cost/endpoint metadata, but says nothing about how 'nearby' is computed or what the targetDate does. Useful but thin beyond 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 core sentence is compact and front-loaded, and the bracketed metadata (group, endpoint, required param, cost) is scannable and earns its space by surfacing the 10-credit cost and required input. Slightly terse rather than padded.

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?

An output schema exists, so return-value detail is not needed, and the required param and cost are stated. What's missing is disambiguation from sibling tools that compute similar age/cycle milestones; otherwise an agent has what it needs 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 coverage is 50%: fields and precision are documented in-schema, while birthDate and targetDate have no descriptions. 'Age-based' weakly implies birthDate and 'nearby' hints at a reference date for targetDate, but neither is stated, so the description only partially compensates for the missing param documentation.

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?

Names a specific resource (age-based wellness milestones) and clarifies it with concrete examples (Saturn return, Uranus opposition, hormonal shifts), which is more informative than the title alone. It does not, however, distinguish itself from overlapping siblings like astroway_family_saturn_return_cycles or astroway_wellness_biorhythm, so an agent must still infer which to call.

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?

There is no explicit when-to-use guidance and no alternatives named, despite the crowded wellness and Saturn-return-adjacent sibling space. The only usage signal is the implicit 'nearby + full list' scope, which describes output rather than when to choose this tool.

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