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

Annotations already declare the full safety profile (readOnly, idempotent, non-destructive, closed-world). The description adds genuinely new behavioral context in the credit cost (10 credits, Tier 1) and the calculation basis. It doesn't explain output, but with an output schema present that gap is acceptable.

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 purpose in one sentence; the group, cost, and alias lines are boilerplate but short and informative. Nothing is padded, though the metadata blocks slightly dilute the signal.

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. However, the relationship to the near-identical non-strict sibling and the role of the required `name` parameter are unexplained, leaving a real selection gap in a very crowded sibling set.

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 50%: `fields` and `precision` are documented inline, while `date` and `name` carry no schema descriptions. The phrase 'from the day-of-birth digit' loosely implies `date`, but the required `name` parameter for a date-derived number is never explained, so the description only marginally compensates.

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 algorithmic basis ('from the day-of-birth digit' in the Kabbalistic Mathers-strict system). The group label distinguishes it from the Chaldean/Pythagorean/Vedic families, though it doesn't explicitly differentiate it from the non-strict `astroway_numerology_kabbalistic_birthday` sibling.

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?

No when-to-use, when-not, or alternative guidance is given. A sibling `..._kabbalistic_birthday` (non-strict) exists, and the description never explains how the 'strict' variant differs or when to prefer it. The agent must infer selection purely from the name.

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