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

With no annotations, the description carries the full burden, and it discloses very little beyond the core operation. The only extra context is the commercial note about five free trial calls per signed wallet, which says nothing about how the tool behaves when the date is omitted, what happens with an invalid weekday number, or what the return value contains.

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 definition is short and front-loaded, but the leading 'Prev Weekday:' label merely restates the tool name, and the trailing free-trial boilerplate is marketing rather than task-relevant information. Roughly half the text is not useful for tool selection.

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 two-parameter date tool with zero schema coverage, no annotations, and no output schema, the description omits essentials: the meaning of the reference date, the accepted weekday numbering convention, and the default behavior given that no parameters are required. An agent cannot call this correctly without guessing.

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% and neither of the two parameters is explained. The phrase 'weekday number' hints that the weekday argument is numeric, but the schema types it as a string and the description never explains the 'date' parameter or what the tool does when both are omitted (required count is 0).

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 and resource: it returns the ISO timestamp of the most recent prior occurrence of a weekday. That is clear enough for an agent to know it is a date-computation tool rather than a validator. However, it does not differentiate itself from the close sibling x402-next-weekday, nor clarify what 'prior' is relative to.

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 the obvious alternative x402-next-weekday, and no statement of prerequisites or defaults. The agent must infer the use case entirely from the tool name.

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