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

Annotations already declare readOnlyHint, idempotentHint, and openWorldHint=false, so the safety profile is covered. The description adds real context beyond that: it discloses exactly which fields are returned (upright and reversed meanings, element, image description) and what input forms are accepted, which matters because there is no output schema.

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 tightly packed sentences with zero waste. The returned content is front-loaded, with accepted input formats following, so an agent gets the essential facts immediately.

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 no output schema, the description takes on the job of describing the return shape and does so adequately for a simple read-only lookup, while annotations cover the safety and idempotency profile. Nothing essential to calling the tool correctly appears missing.

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 information the schema does not: the id range 0–77 and the fact that card names may be given in either English or Lithuanian. The interaction between the card name's language and the lang parameter is left unstated, which holds it back from a 5.

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 states a specific verb and resource: look up the meaning of one tarot card, including upright/reversed meanings, element, and image description. The 'one card' scope implicitly separates it from the draw_cards and draw_clarifier siblings, but it never names them explicitly.

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?

Usage is implied as a direct lookup when you already know which card you want, in contrast to the draw_* siblings which presumably select cards for you. There is no explicit when-to-use/when-not statement or direct mention of an alternative.

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