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

With no annotations, the description carries the behavioral burden. It discloses meaningful traits: the specific three-card spread, the interpretive tradition, the inclusion of 'crisis-response safety boundaries,' and the cost/payment mechanism ('$0.10 per call, paid via x402 (USDC on Base)'). It does not detail response format or disclaimers, but it provides much more than a minimal description.

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 description is compact and every sentence adds value: it states the spread, the deck and tradition, the best-use case, safety boundaries, and cost. The core action is front-loaded and there is no fluff.

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 single-parameter tool with no output schema and no annotations, the description covers the essential operational context: what the tool does, when to use it, safety boundaries, and cost. It lacks explicit exclusion criteria or details about the response format, but the three-card spread description already conveys expected output structure.

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 100% with a clear parameter description ('The question to consult the Tarot about.'), so the schema already documents the only parameter. The description adds some contextual framing ('Best for complex situations...') but does not materially extend parameter semantics 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?

The description identifies a specific verb and resource: 'Consult the Tarot — a three-card Past/Present/Future spread from the Rider-Waite-Smith deck.' It further specifies the interpretive tradition (Waite tradition) and clearly distinguishes this from sibling divination tools by naming the deck, spread structure, and focus.

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 clear usage context: 'Best for complex situations with many moving parts, hidden influences, and psychological depth.' It does not explicitly say when not to use it or compare against sibling tools, so it stops short of full alternative routing, but the guidance is useful and clear.

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