Monthly Horoscope

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

Annotations already declare readOnly/idempotent/non-destructive and closed-world, so the description's added value is the concrete payload contents (ingresses, stations, lunar phases) and the pricing/rate signal ('Cost: 50 credits (Tier 3)'), which is genuinely useful for a paid call. It stops short of explaining output volume or caching behavior.

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 dense and front-loaded, with the distinguishing comparison to the daily tool up front. The bracketed metadata block (group, endpoint, required, cost) is terse and each line carries information, though it reads as scaffolding rather than prose.

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 needn't enumerate return fields, and the 'same shape as the daily one' pointer covers structure economically. Annotations and the cost line cover safety and budget; the only residual gap is that a caller who doesn't know the daily tool's shape gets no fallback description.

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 43%, and the description adds real meaning for `date` (it anchors a 30-day forward window rather than a single day) and confirms `sign` is required. However, it says nothing about `language`, `disclaimer_inline`, or how the documented `style`/`length` options interact with the monthly period, so it only partly compensates 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?

States a specific verb and resource ('Monthly horoscope for a zodiac sign') plus scope ('over 30 days from `date`') and content ('ingresses, stations and lunar phases'). The reference to 'the same shape as the daily one' lets an agent distinguish it from astroway_horoscope_daily/weekly/yearly without opening a schema.

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?

The 30-day window from `date` implies a month-ahead forecast, which is enough to separate it from the daily tool in practice. But it never states when to prefer it over astroway_horoscope_weekly or astroway_horoscope_yearly, nor any prerequisites beyond 'Required: sign'.

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