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. The description adds genuinely new operational context in the form of cost ('10 credits, Tier 1') and group membership, but says nothing about how the seed makes draws reproducible or how allowReversed changes output.

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?

Two short lines, front-loaded with the spread identity, with metadata tags kept to a separate block. Nothing is wasted, though the tags add little for an agent already reading the tool name.

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. However, for a 5-parameter tool with 40% schema coverage and no usage guidance, the description leaves the agent guessing about seed determinism, the question field's role, and reversal behavior.

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 40%: 'fields' and 'precision' are documented in the schema, while 'seed', 'question' and 'allowReversed' are bare. The description contributes no parameter meaning at all, so it fails to compensate for the undocumented half.

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 a specific action and resource ('Classical 10-card Celtic Cross spread') and the deck is fixed by the tool name/title (Rider-Waite-Smith), so an agent can distinguish it from the Marseille or Lenormand Celtic Cross siblings. It stops short of explicitly contrasting itself with the other RWS spreads (three-card, horseshoe, etc.), so it is clear but not sibling-differentiating.

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 mention of alternative spreads or draw tools. The agent must infer from the name alone whether a 10-card Celtic Cross or a lighter three-card draw is appropriate.

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