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 cost transparency (10 credits, Tier 1) and the group tag, which is genuinely useful and beyond structured data, but says nothing about how the birth card is derived or what makes the Greer method distinct.

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?

Extremely short and front-loaded: the purpose leads and the metadata tags follow. Nothing is redundant, though the single fragment is arguably under-specified rather than optimized for concision.

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 values need no explanation, and the tool's mutation-free nature is covered by annotations. What is missing is the meaning of the inputs/output: whether `date` is a birth date and how the Greer birth card is calculated, leaving the agent to guess at intent.

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 67%: `fields` and `precision` are documented in the schema, while the required `date` carries only a pattern and no semantic explanation. The description contributes nothing about parameters, so this is the baseline case where the schema does the heavy lifting.

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 the specific resource (birth card), the calculation method (Greer), and the deck (Marseille), which implicitly separates it from the parallel rider_waite_birth_card sibling. It lacks a verb (compute/generate) and never names an alternative explicitly, but the resource is unmistakable.

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 when-to-use guidance, no prerequisites, and no routing to the many sibling tarot tools (e.g. astroway_tarot_marseille_year_card or astroway_tarot_rider_waite_birth_card). The agent must infer selection criteria from the name alone.

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