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

The annotations already declare readOnlyHint, idempotentHint, non-destructive and closed-world, so the safety profile is fully covered by structured data. The description adds genuinely new context — that there are exactly 12 definitions and that the call costs 10 credits (Tier 1) — but says nothing about pagination, response shape, or caching, which is acceptable given the output schema exists.

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 key fact — what the tool returns and how many — is front-loaded in a single sentence, followed by structured group/cost tags that are easy to scan. No wasted prose, though the metadata lines are boilerplate rather than explanatory.

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, the description needn't explain return values, and the annotations cover safety, so the remaining gap is the missing routing guidance to the slug/draw siblings. Adequate but not complete for a catalog-style listing tool sitting among many tarot siblings.

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 100%, and the two parameters (fields, precision) are fully documented in the schema itself, including the dotted-path syntax and decimal-rounding semantics. The description adds nothing about parameters, so the baseline 3 applies.

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 and resource ('List of all 12 RWS spread definitions') with a concrete count, which tells an agent exactly what comes back. It does not explicitly name the near-identical sibling astroway_tarot_rider_waite_spreads_slug, so the boundary between 'all spreads' and 'look up one spread by slug' is left to inference from the name alone.

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 gives no when-to-use guidance, no prerequisites, and no mention of the sibling that fetches a single spread by slug. An agent must guess whether this is the right entry point versus astroway_tarot_rider_waite_spreads_slug or the individual draw_* spread tools.

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