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

Annotations already declare readOnlyHint=true, so the description doesn't need to cover safety. It adds value by describing the output structure (core numbers 1–22, text interpretations) and the scope (personality, talents, money, relationships, etc.), which goes beyond the basic read-only nature.

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?

The description is two well-structured sentences that front-load the main purpose, then detail the output, and finish with a usage guideline. No wasted words, and the key information is presented efficiently.

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?

There is no output schema, so the description takes on the burden of describing return values. It does so thoroughly (core numbers, interpretation categories). However, it doesn't mention edge cases like invalid date formats or whether the locale parameter affects the output format, leaving minor gaps.

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 the schema already documents both parameters (birthdate and locale). The description mentions 'single date of birth' but adds no additional parameter semantics beyond the schema, earning the baseline score of 3.

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 clearly states the tool calculates a Destiny Matrix from a date of birth and returns a structured numerology reading with specific components (core numbers, personality, talents, etc.). It also explicitly distinguishes its use case from the sibling tool by mentioning 'numerology personality reading based on a birth date.'

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 provides an explicit 'Use this when...' clause listing the relevant user requests. However, it does not directly mention when not to use it or name the sibling tool (calculate_compatibility) as an alternative, leaving some ambiguity.

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