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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint false, so the safety profile is clear. The description adds useful behavioral context: it works across all Arcanika decks with per-deck meaning variations, and returns multiple dimensions (love, career, advice, etc.) in both upright and reversed positions. No contradictions with 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?

Two concise sentences that front-load the core purpose and immediately clarify the single-card scope and pointer to start_reading for multi-card spreads. No filler or redundant information.

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 read-only lookup tool with no output schema, the description adequately describes what the response will contain (meaning sections, upright/reversed, deck-specific) and clarifies constraints (one card only, paid multi-card alternative). It fully equips the agent for invocation.

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 detailed parameter descriptions (e.g., card name/slug formats, deck slug from list_decks, locale enum with defaults). The description repeats some of this (e.g., deck slug reference) but adds no significant new meaning beyond the schema, so a baseline score is appropriate.

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 clearly states the tool returns the meaning of one Tarot card with specific sections (keywords, general, love, career, advice) in both upright and reversed positions. It explicitly distinguishes from the sibling 'start_reading' tool by stating it's for a single card, and from 'calculate_matrix' and 'calculate_pythagoras' by focusing on card meanings.

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?

Provides explicit guidance: works with any Arcanika deck, and directs users to 'start_reading' for multi-card readings (which is a paid product). Also references 'list_decks' for obtaining deck slugs, giving clear context on when to use this tool versus alternatives.

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