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

Annotations already declare this a safe, idempotent, non-destructive read, so the safety profile is covered. The description adds only the group tag and a billing cost (10 credits, Tier 1), which is genuinely useful call-planning context, but it says nothing about the shape or size of the returned catalog; with an output schema present that gap is tolerable.

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 sentence states the scope, followed by compact metadata lines for group and cost. Nothing is padded, though the description is arguably under-specified rather than optimally concise.

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 simple catalog lookup with an output schema and full parameter documentation, the minimum is met: the agent knows what it returns and what it costs. It stops short of clarifying depth of card data (keywords, imagery, meanings) or how it differs concretely from the full-deck sibling.

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?

Both parameters (fields, precision) have full schema descriptions at 100% coverage, so the schema carries the semantics. The description contributes nothing about parameters beyond the compact-mode mechanics already documented, which is the expected baseline when coverage is high.

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 names the specific resource (the 22 Major Arcana cards) and the subset boundary with 'only,' which implicitly separates it from astroway_tarot_rider_waite_minors and astroway_tarot_rider_waite_courts. It does not name those siblings by name or state that it is a catalog/listing operation, but the scope is unambiguous.

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 word 'only' hints that this is the narrow, Majors-restricted variant, implying when to pick it over the full-deck tool, but no alternative is named and no explicit when/when-not guidance is given. Usage is inferable from the sibling names rather than stated.

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