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

Annotations already declare read-only, idempotent, closed-world and non-destructive behavior, so the safety profile is fully covered. The description adds genuinely useful context the annotations lack, namely the pricing metadata ("10 credits (Tier 1)"), but says nothing about how the number is derived or what errors occur for malformed input.

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?

Two short lines, front-loaded with the core action, then the group and cost tags. Nothing reads as padding, though the bracketed metadata is terse rather than explanatory.

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 annotations cover the safety profile. The remaining deficits are the unexplained `name` parameter and the missing distinction from the strict Kabbalistic birthday sibling, which leaves the definition only marginally complete.

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 coverage is only 50%: `fields` and `precision` are documented, but `date` and `name` – both required – carry no descriptions. The phrase "from the day-of-birth digit" hints at date usage but the description never explains why `name` is required for a day-of-birth calculation, leaving the highest-value gap unfilled.

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 ("Calculate the Birthday number") plus the system ("Kabbalistic (phonetic)"), which separates it from the Chaldean, Pythagorean and Vedic birthday siblings. It does not, however, distinguish itself from astroway_numerology_kabbalistic_strict_birthday, so an agent still has to guess between the two.

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?

There is no explicit when-to-use or when-not-to-use guidance. The system label only weakly implies the selection criterion, and the near-identical strict variant in the sibling list is never mentioned, leaving the agent to infer which birthday tool applies.

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