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

Annotations already declare readOnly, idempotent, closed-world, non-destructive behavior, so the safety profile is covered. The description adds genuine context beyond that: it names the calculation method and its boundary condition (Lunar calendar year determined by the Tết/Lunar New Year boundary) and discloses the output content (governing virtues, spiritual strengths, invocation prayer). It does not discuss error handling for malformed dates.

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?

Three sentences, front-loaded with the core capability, then the calculation nuance, then the payoff. Minor marketing residue ('sacred invocation prayer', 'lifelong') but nothing structurally wasteful or out of order.

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?

For a one-parameter, read-only divination lookup with no output schema, the description covers what it computes, how the input is interpreted, and what categories of result come back. Only edge behavior (e.g. invalid or ambiguous dates, response shape) is left unaddressed, which is a modest gap at this complexity.

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 100% and there is a single parameter, so the baseline is 3. The description earns above baseline by explaining the behavioral consequence of the two accepted input forms — that supplying a full year triggers exact Lunar-year resolution against the Tết boundary, which the schema does not convey.

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 (identify) and two specific resources (Guardian Angel from the 72 Kabbalistic Angels / Shem HaMephorash, and Patron Bodhisattva / Bát Đại Bản Mệnh Phật) derived from birth date. This is clearly separable from siblings like calculate_numerology, bazi_chart, or tuvi_chart_vn without opening any 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?

Usage is implied rather than stated: an agent can infer this applies when a user asks about guardian angels or patron buddhas. There is no explicit when-not guidance and none of the 20 sibling tools are named or ruled out (e.g. versus calculate_numerology or decode_angel_number), leaving routing to inference.

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