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

Annotations already declare readOnly=false, idempotent=false, destructive=false, openWorld=true, so the safety profile is covered. The description adds material behavioral context beyond that: the 250-credit Tier 5 cost and the requirement to confirm with the user first, which is genuinely decision-relevant. It does not describe side effects or result handling, keeping it out of 5 territory.

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 purpose is front-loaded, then structured metadata lines (group, endpoint, required, cost) carry the rest with no filler. Every line earns its place, though the bracketed tag block is somewhat boilerplate rather than prose that aids selection.

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 an output schema present, the description need not explain return values, and it covers purpose, required inputs, cost and a confirmation warning. The main gap is that two optional parameters (fields, precision) and the tone/length/language semantics are left entirely to the schema.

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 only 38%, so the description is expected to compensate. It lists chart, year, month, language, tone and length as inputs but adds meaning only for month ('1-12'), leaving fields and precision unmentioned and tone/length/language values unexplained. This is minimum-viable, not compensating for the coverage gap.

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 names a concrete resource ('single-month forecast') and explicitly scopes it ('uses fast and slow planet transits within the month'), which lets an agent separate it from the year-ahead sibling. The verb is implicit rather than stated ('generate a narrative'), but the purpose is unambiguous.

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 contrasts scope with the year-ahead sibling ('Tighter scope than year-ahead'), giving a selection cue, and adds a strong operational directive: 'Heavy — confirm with user before invoking' at Tier 5 / 250 credits. No exclusion rules against the natal/synastry/transit narrative siblings are given, so it falls short of a 5.

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