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

Annotations already declare readOnlyHint, idempotentHint and destructiveHint=false, so the safety profile is covered. The description adds genuinely useful non-annotation context — endpoint, required inputs, and a 10-credit Tier 1 cost — but says nothing about name normalization, failure behavior, or why a date is needed for a name-derived number.

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?

One tight sentence with the operation front-loaded, followed by a compact metadata block. The bracketed lines are boilerplate but each carries a distinct fact (group, endpoint, required params, cost), so little 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-shape explanation is correctly omitted, and annotations cover the safety profile. The remaining gaps are the unexplained role of 'date' and the absence of routing guidance against the strict and other-system expression siblings, which matters in a family this dense.

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 self-documented, while 'date' and 'name' are not. The description partially compensates by stating both are required and clarifying that the full birth name is used with all letters counted, but it never explains what 'date' represents (birth date?) for a calculation driven by name letters.

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?

The description names a specific verb and resource ('Calculate the Expression (Destiny) number') and pins the system as 'Kabbalistic (phonetic)'. That differentiates it from the Chaldean, Pythagorean and Vedic expression siblings, though it never addresses the near-identical astroway_numerology_kabbalistic_strict_expression, which is the sibling an agent is most likely to confuse it with.

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 only implied: the '(phonetic)' label and '(all letters, reduced)' method identify the variant, so an agent can infer this is the phonetic-Kabbalistic variant rather than the strict one. There is no explicit when-to-use statement, no exclusion of the strict/Chaldean/Pythagorean alternatives, and no prerequisite guidance.

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