Marseille: Birth Card

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

Annotations already declare readOnlyHint, idempotentHint, non-destructive and closed-world, so safety is covered. The description adds genuinely new behavioral facts: POST endpoint, required input, and a 10-credit (Tier 1) cost, which is exactly the kind of billing context annotations can't express.

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 single substantive sentence is front-loaded and zero-waste; the metadata block is compact and scannable. Slightly under-specified rather than verbose, but nothing is padded.

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?

Output schema exists so return values needn't be explained, and annotations cover safety, leaving cost/endpoint as the useful additions. Still missing is any explanation of what a Greer-method birth card is (numeric reduction to a major?) and how it differs from the RWS birth card sibling.

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 50%: 'art' is fully documented in the schema, and 'date' carries a YYYY-MM-DD pattern, so the gap is small. The description's only param contribution is restating 'Required: date', without clarifying that the date is a birth date rather than an event date or a year-card year.

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 computation (birth card) with the method (Greer) and the deck (Marseille), which is enough to distinguish it from the RWS variant astroway_tarot_rider_waite_birth_card. It never explicitly names that sibling or says how the two differ in output, so differentiation is implicit 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?

There is no when-to-use guidance: nothing says to pick this over the Rider-Waite birth card, or over Marseille year_card/timing tools. The bracketed metadata (group, endpoint, required, cost) is structured plumbing, not usage guidance, so the agent must infer suitability 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.