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

Annotations already declare readOnlyHint, idempotentHint, non-destructive and closed-world, so the safety profile is fully covered. The description adds genuinely useful operational context — the 10-credit Tier 1 cost and the canonical-vs-alias relationship — but says nothing about computation basis, period depth, or what the 'years' horizon affects.

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?

Four short front-loaded lines with no filler: what it computes first, then grouping, cost, and alias identity. The bracketed tag format is dense and scannable; 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?

An output schema exists and annotations fully cover safety, and the input schema is richly self-documenting, so the description need not explain returns. What is missing is the disambiguation an agent needs among the clustered ZR siblings, which is the main residual gap.

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% and the nested birth-data object documents formats, timezone handling, rejected short forms and houseSystem letters in detail. The description adds no parameter meaning beyond that, so the baseline 3 applies.

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 specific technique and resource ('Zodiacal Releasing from Lot of Spirit') plus the interpretive domain ('career/action periods'), and identifies itself as an alias for astroway_hellenistic_brennan_zodiacal_releasing_spirit. It does not, however, distinguish itself from the close sibling astroway_helb_zodiacal_releasing_fortune, leaving the Spirit-vs-Fortune choice implicit.

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?

'career/action periods' implies the topical context in which to reach for this tool, but there is no explicit when-to-use, when-not, or named alternative even though two near-identical siblings (zodiacal_releasing_fortune, zr_peak_periods) exist. Usage is inferable rather than stated.

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