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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint false. The description adds substantial behavioral detail beyond that: cards are dealt without replacement using cryptographic randomness, each position returns card/orientation/keywords, and Major Arcana/reversed counts are included. It also manages expectations with 'not prediction,' which is valuable context.

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 front-loaded: action and method first, then spread options, then output shape, then purpose caveat and source. Every sentence conveys useful information without repetition or filler.

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 tarot tool with an output schema and safety annotations, the description covers everything an agent needs: the deck, randomness, spread choices, output contents, and appropriate use. It is fully self-contained and leaves no material gap for selecting or invoking the tool correctly.

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%, so the baseline is 3, but the description adds significant meaning by mapping every spread enum value to its card count and positional meaning. This helps an agent select the right spread much more effectively than the bare enum names alone. The reversed parameter is already clear from the schema, and the description reinforces it by mentioning orientation and reversed-card counts.

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 starts with a specific verb and resource: 'Draw a tarot spread from all 78 Rider-Waite-Smith cards.' It goes far beyond the title by naming the deck, the dealing method, and all supported spread types, so an agent can clearly identify what the tool does and how it differs from other random/generator tools.

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: it is 'for reflection and fun, not prediction,' and it enumerates the exact supported spreads. It does not explicitly name sibling alternatives or say when to choose this over fortune_cookie, magic_8_ball, or other random tools, so it stops short of a 5.

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