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

Annotations already declare readOnly/destructive/idempotent and openWorld behavior, so the safety profile is covered. The description adds meaningful context beyond that: master-number handling, that the output names the system used, and that birth date and name are not stored — a privacy commitment an agent cannot infer from structured fields.

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 tight sentences, front-loaded with the core verb+resource. Slight redundancy in restating the non-storage guarantee, but every sentence carries information with no filler.

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?

With an output schema present, return values need not be explained. The description covers scope, systems, master-number behavior, and privacy, leaving little an agent needs beyond the schema — only minor gaps like default system behavior remain.

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%, so all three parameters (system enum, full_name, birth_date with format) are already documented in the schema. The description mentions the Pythagorean/Chaldean choice but adds no format or constraint detail beyond what the schema provides; baseline 3 applies.

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+resource ('calculate core numerology numbers') and enumerates the exact outputs (life path, expression, soul urge, personality) plus the two calculation systems. An agent knows precisely what this tool produces; the unrelated sibling tools pose no ambiguity.

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 description sets a scope boundary ('Entertainment and personal reflection only'), which implies when the tool is appropriate, but gives no explicit when-to-use/when-not conditions or alternatives. Given there are no comparable sibling tools, the implied usage is adequate but thin.

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