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

Goes well beyond the annotations, which only declare a safe read operation. It discloses that shuffling is server-side, that the widget path deliberately omits the drawn cards from the tool result and delivers them later via the conversation, and that text-only hosts return cards directly — behavior an agent must know to interpret the response.

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?

Front-loads the core action, then the host-dependent behavior, then parameter usage; every sentence carries information. It is dense and slightly long, but no sentence is filler given the non-obvious widget/text-only split.

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 not be described, yet the description supplies the one thing the schema cannot: that the result may intentionally contain no cards in widget hosts. Combined with locale and spread routing, an agent has everything needed to call and interpret it.

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 the schema already documents locale format, spread_id precedence, and the 1-10 card_count bound with its default, so the baseline is 3. The description restates spread_id's source and the card_count range without adding syntax or validation detail the schema lacks.

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?

States a specific verb+resource (shuffle/draw a 78-card Rider-Waite-Smith tarot deck) and immediately distinguishes itself from the only sibling by naming list_spreads as the source of spread_id. An agent can tell what this does and that it is not the listing tool without opening the schema.

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 a clear selection rule between the two draw modes: spread_id for drawing into a spread's positions, card_count for free-form draws like a card of the day, with an example. It routes to list_spreads for obtaining a spread_id, but never states when this tool should not be used or what happens if both params are omitted beyond the schema default.

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