Marseille: Single Card

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

Annotations already declare readOnly, idempotent, closed-world and non-destructive, so safety is fully covered. The description adds genuinely new context: the cost is not in the public credit manifest and should be checked against the plan, which is useful billing uncertainty for an agent. It adds nothing on return shape, but an output schema exists.

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?

One-sentence purpose followed by tagged metadata, front-loaded and easy to scan. The endpoint path and group tags are mild noise for an agent but don't crowd out the useful content.

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 single-parameter read lookup with full annotations and an output schema, the description covers what is needed: purpose, key type, and a cost caveat. Only the fallback to the list endpoint for discovering slugs is left implicit.

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% and the schema already specifies 'lowercase and hyphenated' slugs; the '[Required: slug]' tag merely repeats the required array. Baseline 3 applies when the schema carries the parameter detail.

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 and resource ('Single Marseille card lookup by slug'), and the 'single' plus slug key distinguish it from the sibling astroway_tarot_marseille_cards list endpoint. It does not explicitly name the sibling, so sibling differentiation is implied rather than stated.

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 by 'lookup by slug' – an agent can infer it needs a known slug and should use the list tool to find one – but no alternative is named and there is no explicit when/when-not guidance.

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