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

No annotations are provided, so the description carries the full burden. It contains zero behavioral context: it doesn't state whether the operation is a read (likely), what happens if 'date' is omitted (both parameters are optional), how 'weekday' is interpreted, or what the return value looks like. For a tool with no annotations and no output schema, this is completely inadequate.

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 extremely short, but not in a helpful way – it's a tautological repetition of the title rather than a concise summary. It doesn't front-load any useful information because there is none. Brevity without substance scores low.

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?

With no annotations, no output schema, and a trivial description, the definition is missing almost everything an agent needs to invoke the tool correctly. The 2-parameter schema is the only source of information, and it's minimal. The description should at least explain what 'previous weekday' means and how the date/weekday inputs combine.

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%, so the schema already documents both parameters ('Date to process' and 'Weekday to process'). The description adds no additional meaning beyond the schema's terse one-liners. Baseline 3 is appropriate when the schema does all the work, though the schema itself is vague.

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 is a tautology: 'Prev Weekday: Prev Weekday' simply restates the tool name without adding a specific verb or clarifying what operation is performed. It's implied that it returns the previous weekday relative to a date, but the description never states this explicitly. Sibling tools like x402-next-weekday exist, so differentiation matters, and this text fails to provide it.

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?

No when-to-use guidance is provided. The description doesn't explain that this tool should be used to find the weekday immediately preceding a given date, nor does it mention the alternative x402-next-weekday or x402-is-weekend-date. An agent must infer usage 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.