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 genuinely useful non-annotation context: the endpoint, required inputs, and a cost of 10 credits (Tier 1), which matters for an agent budgeting calls. It does not, however, describe output shape, error behavior, or rate limits.

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, followed by a compact bracketed metadata block. Every line carries information (group, endpoint, required fields, cost) with no filler. It is slightly repetitive in restating required params already implied by the schema.

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-value explanation is not needed, and cost/endpoint/required fields are present. However, for a tool sitting among ~10 near-identical numerology siblings, the definition lacks the disambiguation an agent needs to select it correctly, leaving a meaningful gap.

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%: 'fields' and 'precision' are documented in the schema, while 'name' and 'date' rely on their types/pattern/minLength constraints. The description restates only that name and date are required and adds no format or semantic detail (e.g., whether name affects the calculation or is only for labeling). Baseline 3 is appropriate.

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 gives a specific verb+resource ("Calculate the Birthday number") and names the system (Pythagorean), which is the key differentiator against the many sibling numerology tools (Chaldean, Kabbalistic, Vedic, numks/nump). The phrase "from the day-of-birth digit" is slightly imprecise but does not obscure the purpose. It stops short of explicitly contrasting itself with the Birthday siblings of other systems, so it earns a 4 rather than a 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 pick this tool over the pythagorean_chart, life_path, or the chaldean/kabbalistic/vedic birthday variants. The metadata block supplies group, endpoint, and cost but no selection criteria or exclusions. The agent must infer usage 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.