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

Annotations already declare readOnlyHint, idempotentHint, non-destructive and non-open-world, so the safety profile is covered. The description adds a group label and a cost caveat ('see your plan — endpoint not in the public credit manifest'), which is genuinely useful context but does not disclose return behavior or rate limits.

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 core sentence is front-loaded and waste-free. The bracketed group and cost lines are boilerplate but short and clearly separated from the functional description.

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 simple single-record lookup with a full output schema, complete param coverage and annotations covering the safety profile, the description supplies enough. Only the absence of sibling routing keeps it from being fully complete.

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%, so slug, fields and precision are already fully documented in the schema. The description adds only 'by slug' and nothing about the compact-mode fields/precision parameters, so baseline 3 applies.

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: 'Single Lenormand card lookup by slug.' The words 'Single' and 'by slug' distinguish it from the sibling list tool astroway_tarot_lenormand_cards, though the sibling is never named 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?

No when-to-use guidance, no mention of alternatives such as the plural cards list or the draw_* spread tools. The agent must infer that this fetches one card's record from the name alone.

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