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

Annotations already establish read-only, idempotent, non-destructive behavior, so the description's added value is the cost disclosure (20 credits, Tier 2) and the localization contract: every number carries `meaning` plus `meaningLocalized`, with `translated: false` returning English while a language's strings are being prepared. That fallback behavior is the kind of thing an agent could not infer from structured fields.

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?

Front-loads the core value proposition (six numbers in one call) and then layers cost and localization in tight sentences. Slightly dense with parenthetical caveats, but every clause carries information an agent needs.

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?

For a 5-parameter computation tool with annotations and an output schema, this is nearly complete: it covers the member set, cost, localization, and the year default. The only gap is silence on the `fields`/`precision` compact-mode controls, which are relevant given the tool returns a large nested payload.

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 60%, so `year`, `fields` and `precision` are documented in the schema while `name` and `date` are not. The description clarifies that `year` defaults to the current year and confirms `name`/`date` are required, but says nothing about the `fields`/`precision` compact-mode parameters, leaving the schema to carry them. Baseline 3 fits when the schema does most of the lifting.

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?

States a concrete verb+resource: returns the six core numbers (Life Path, Expression, Soul Urge, Personality, Birthday, Personal Year) in one call, under the Chaldean system. The enumeration lets an agent distinguish it immediately from the single-number siblings like astroway_numerology_chaldean_life_path. It also names the sibling it supersedes ('six single calls').

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 makes the selection case clear by contrasting cost: '20 credits instead of 60 for six single calls', which routes an agent wanting a full chart here rather than making six separate calls. It stops short of an explicit 'use X when / don't use Y when' statement or naming the individual sibling tools, so it is strong context rather than full guidance.

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