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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so the safety profile is covered by structured data. The description adds genuinely useful non-annotation context: the cost (10 credits, Tier 1) and the underlying endpoint, which helps with budgeting and tracing. It says nothing further about pagination or response size, so it is adequate rather than rich.

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, with the endpoint/group/cost metadata compactly bracketed below. Nothing is padded, though the bracketed metadata is templated and contributes less than the opening sentence.

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 explained, and the two optional params are fully documented in the schema. What is missing is routing context: in a catalog with 'spreads' and 'spreads_slug' sitting next to each other, the description should say which to pick, and it does not.

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% – both 'fields' and 'precision' are fully documented in the input schema, including examples and defaults. The description adds no parameter guidance beyond that, so the baseline of 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?

The description gives a specific verb+resource ('List of all Marseille spreads') and even names an included item (Jodorowsky cross), so the agent knows exactly what it returns. It does not, however, distinguish itself from the sibling astroway_tarot_marseille_spreads_slug, leaving the 'all vs. one' distinction to be inferred from the name.

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, no mention of prerequisites, and no pointer to the obvious alternative (astroway_tarot_marseille_spreads_slug) for fetching a single spread. The agent must infer usage entirely from the name and title.

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