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

Annotations already cover safety (readOnly, non-destructive, non-idempotent) and open-world behavior, so the bar is lower. The description adds genuinely useful behavior: deck shuffle with reversals, spread sizes, that a reflective note is written, and that the question is not stored — the latter being a privacy trait not visible in annotations.

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?

Three tightly packed sentences with no filler; the core operation is front-loaded and the disclaimer/privacy clauses are compressed into short trailing statements that each earn their place.

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 it appropriately notes that a reflective note is produced. It is essentially complete for a 2-parameter tool; only a hint about the note's format or delivery is absent, which the output schema likely covers.

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 both parameters are documented there, so the schema carries the load and baseline 3 applies. The description restates spread sizes (one/three/five, matching the enum) and reinforces 'question not stored', adding only marginal meaning beyond the schema.

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?

Names a specific verb and resource ('draw cards', 'tarot reading') and specifies the exact scope: a 78-card deck, upright/reversed, one/three/five card spread. An agent immediately understands the operation and its output (a short reflective note).

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?

Gives clear usage context ('for a question you ask') and an explicit boundary ('Entertainment only, not a prediction and not advice'), which tells the agent when this is appropriate. It does not name alternatives, though the siblings (feedback/index tools) are unrelated, so routing guidance is less critical.

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