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 safety profile is covered. The description adds genuinely useful non-annotation context — cost ('10 credits (Tier 1)') and the required-parameter list — but says nothing about authentication, rate limits, or what the computation consumes (e.g., whether 'name' actually influences the result).

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-loaded with the core action in the first sentence, and the bracketed metadata lines are compact and scannable rather than prose padding. Slightly fragmented structure, but 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, so return values need not be described, and the annotations carry the safety profile. However, for a tool sitting in a dense family of near-identical siblings, the description omits the strict-vs-non-strict distinction and the role of the 'name' parameter, which are the two things an agent most needs.

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 50%: 'fields' and 'precision' are documented in the schema while 'date' and 'name' are not. The description adds one hint — that the number derives from the 'day-of-birth digit' — but does not explain why 'name' is required for a day-digit calculation, leaving a real semantic gap. Baseline 3 is appropriate at this coverage level.

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 ('Calculate') and resource ('Birthday number from the day-of-birth digit') and names the divination system ('Kabbalistic (Mathers strict) system'), which is the key discriminator among the many numerology siblings. It falls short of a 5 because it never explicitly distinguishes itself from astroway_numerology_kabbalistic_birthday (non-strict) or astroway_numks_birthday, which an agent must otherwise infer.

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 system label ('Kabbalistic (Mathers strict)') and the endpoint path give implied selection context among the Chaldean/Pythagorean/Vedic/Kabbalistic variants. There is no explicit when-to-use statement, no condition that selects the strict variant over the plain Kabbalistic one, and no exclusion guidance.

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