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

Annotations already declare readOnlyHint, idempotentHint, non-destructive, and closed-world, so the safety profile is covered without the text. The description does add genuine context beyond the annotations, notably the '10 credits (Tier 1)' cost and the POST endpoint, but it says nothing about failure modes, invalid-date behavior, or whether results are cached/reproducible.

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 front-loaded purpose sentence followed by a compact bracketed metadata block; nothing is padded or repeated. The metadata lines are somewhat boilerplate, which keeps it just short of ideal, but the whole definition is scannable in one pass.

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?

Because an output schema exists, the description need not explain return values, and the read-only annotations cover the safety story, so the remaining burden is light. What is missing is the cross-system selection logic in a family of ~30 near-identically named numerology siblings, which is the main risk for an agent choosing this tool.

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 50%: 'fields' and 'precision' are documented in the schema, while 'date' and 'name' are not. The description's 'Required: name, date' merely restates the schema's required array, and the only real semantic addition is the hint that the day-of-birth digit drives the result. It never explains the YYYY-MM-DD format requirement or the name length bound.

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 pairs a specific verb and resource ('Calculate the Birthday number') with the system scoping ('Vedic system') and the derivation rule ('from the day-of-birth digit'). That last clause cleanly separates it from siblings like astroway_numerology_pythagorean_birthday and from other Vedic tools such as vedic_life_path or vedic_expression, which use different inputs.

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 description states what the tool computes but never says when to pick this Vedic variant over the Chaldean, Kabbalistic, or Pythagorean birthday siblings, nor when a birthday number is the wrong reading to request. The only usage-adjacent content is the bracketed 'Required: name, date' and cost line, which are preconditions rather than selection guidance.

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