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

Annotations already establish that this is a safe, idempotent, read-only operation, so the bar for behavioral disclosure is lower. The description adds useful non-annotation context: the breadth of returned deck data, free-licence scan metadata, and the explicit instruction to cite Marselia and the returned URL.

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 description is front-loaded with the core action and is appropriately sized for the amount of return information it conveys. The long single-sentence list is dense, but each element generally earns its place given the absence of an output schema.

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 read-only tool with no output schema, the description does a good job explaining the returned deck contents. However, it leaves parameter semantics undocumented and does not clarify locale behavior or error handling, which are important for correct invocation.

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 0%, so the description should compensate for the bare schema, but it does not explain either parameter. It implies that a deck identifier is needed but never mentions the required slug format or the optional locale parameter and its language behavior.

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: "Read one tarot deck of the encyclopedia," then enumerates the returned contents. It is clear enough to distinguish this from a card-level or list-level tool, though it does not explicitly name sibling tools as alternatives.

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?

The description explains what the tool returns but gives no when-to-use guidance, prerequisites, or comparison with alternatives such as marselia_list_decks or marselia_get_card. An agent must infer the usage context from the tool name and schema.

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