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

Annotations already declare readOnly, idempotent, non-destructive, closed-world behavior, so the safety profile is covered. The description adds the genuinely useful non-structured fact that a call costs 10 credits (Tier 1), but says nothing about the calculation's inputs/outputs beyond that; with an output schema present, that omission is tolerable.

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 verb and resource front-loaded, followed by compact metadata tags. No filler; the only quibble is that the metadata lines consume space that could have carried missing parameter context.

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 no explanation, and annotations cover the safety profile. However, the required 'name' and 'date' inputs remain opaque, which is a real gap for a tool whose siblings share near-identical signatures and must be told apart.

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%: only 'fields' and 'precision' are documented in the schema. The two required parameters, 'name' and 'date', are unexplained anywhere, and the phrase 'day-of-birth digit' vaguely gestures at date without clarifying format, timezone, or why a name is mandatory for a birthday-number calculation.

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 ('Calculate') and resource ('Birthday number') and pins the variant with 'Numerology: Chaldean system', which lets an agent separate it from the kabbalistic/pythagorean/vedic birthday siblings. The only slight ambiguity is 'from the day-of-birth digit', which undersells that the tool also consumes a required name.

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 guidance on when to choose this over the ~60 sibling numerology tools, nor any prerequisites or exclusions. The group/cost metadata is present but it is not usage routing, so the agent must infer selection from the tool name alone.

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