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 usefully adds the credit cost and tier, but it does not explain why the required 'name' parameter is needed for what it describes as a day-of-birth digit calculation, leaving an unexplained requirement.

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 compact sentence plus two metadata tags, front-loaded with the action and the system. No filler, though the group/cost tags are template boilerplate rather than prose.

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 and rich annotations mean return values and safety need not be restated, and cost is covered. What is missing is any disambiguation from the many near-identical Birthday siblings and any explanation of the mandatory `name` input.

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 documented in the schema, but `name` and `date` are not. The description only vaguely gestures at the day ('day-of-birth digit') and says nothing about the role or constraints of the required `name`, so it fails to compensate for the coverage gap.

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 and resource ('Calculate the Birthday number') and pins the system ('Kabbalistic (Mathers strict)'), which is exactly what distinguishes it from the numerous chaldean/pythagorean/vedic/kabbalistic-non-strict Birthday siblings. It stops short of explicitly contrasting with the closest sibling astroway_numerology_kabbalistic_birthday, but the group tag carries most of that load.

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 by the name and system label, and the cost tag tells the agent this consumes 10 credits (Tier 1), which is real decision-relevant context. There is no explicit when-to-use or when-to-prefer-an-alternative statement among the ~10 parallel Birthday tools.

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