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

Annotations already declare readOnly=true, idempotent=true, destructive=false, closed-world, so the safety profile is covered. The description adds a genuinely useful behavioral trait not in the annotations: the cost (10 credits, Tier 1) and the endpoint. It does not describe what the computation returns or how it behaves, but with annotations carrying safety and an output schema present, this is a solid addition.

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 core purpose is front-loaded in the first sentence, and the bracketed metadata (group, endpoint, required, cost) is compact and skimmable. No sentence is wasted, though the metadata block is fairly boilerplate rather than high-value 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?

With an output schema present, return values need no explanation, and the annotations cover the safety profile. The description adds required params, cost, and endpoint, which is close to complete for a single-value calculation tool. The notable gap is the absence of any cross-system disambiguation, which is what keeps it from 5.

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-schema, while 'name' and 'date' have no descriptions. The description lists the two required params and hints that 'date' supplies the day-of-birth digit, adding modest meaning, but it does not explain format, constraints, or the compact-mode params. A 3 is appropriate given the schema does part of the work.

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 the Birthday number') and pins the system via 'Numerology: Chaldean' plus the group tag, which separates it from the many sibling *_birthday tools (kabbalistic, pythagorean, vedic, numks). 'From the day-of-birth digit' clarifies the input semantics beyond the bare name. It stops short of contrasting the output with other systems' birthday numbers, so 4 rather than 5.

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?

There is no guidance on when to choose this Chaldean birthday tool over pythagorean_birthday, kabbalistic_birthday, or vedic_birthday, nor any prerequisite or exclusion. The metadata block lists required params and cost but never frames selection context. An agent must infer the choice purely from the tool name.

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