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

Annotations already declare readOnly/idempotent/non-destructive/closed-world, so the safety profile is covered. The description adds genuinely useful operational context the annotations lack: a cost of 10 credits (Tier 1), the required inputs, and the POST endpoint. It does not describe output shape, but an output schema exists.

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 lead sentence is front-loaded and the metadata block is scannable, with no filler prose. Minor waste in repeating 'Required: name, date' already present in the schema, but overall tight.

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?

For a read-only calculation tool with an output schema, the definition supplies system identity, cost, endpoint, required inputs, and the alias relationship. The main residual gap is that the two required string parameters (name, date) get no format or meaning guidance anywhere.

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 only 60%: `year`, `fields`, and `precision` are documented in the schema, while `name` and `date` are not. The description adds no semantics for those two beyond restating 'Required: name, date', which duplicates the schema's required list, and 'given calendar year' only loosely gestures at the year parameter.

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), resource (Personal Year number), and scope (for a given calendar year, the 9-year cycle), then pins the exact system variant 'Kabbalistic (Mathers strict)'. Against siblings that split into chaldean/pythagorean/vedic and a non-strict kabbalistic line, an agent can pick this one without opening a schema.

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 system label implicitly routes the agent within the numerology family, and the alias note tells it when this name is the one to call. But there is no explicit when-to-use versus the sibling variants (chaldean/kabbalistic/pythagorean personal_year) or when to prefer this over the long-form canonical name.

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