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

No annotations are provided, so the description carries full responsibility for behavioral disclosure. It discloses nothing: no mention of what is computed, whether it expects a date string, what format is required, or what the output represents. The description is behaviorally opaque.

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 text is short but this is under-specification rather than conciseness. 'Days In Month: Days In Month' contains zero informative content and does not earn its place. No useful information is front-loaded because none exists.

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 single vague parameter, the description needed to explain the input format, what the tool returns, and how it relates to sibling tools. It does none of this, so an agent cannot reliably invoke the tool correctly.

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% for the single 'date' parameter, but the schema only says 'Date to process' with no format or example. The description adds no additional meaning beyond the schema. Baseline 3 applies because the schema covers the parameter, but the minimal 'Date to process' leaves the agent guessing about formatting.

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 'Days In Month: Days In Month' is a pure tautology that simply restates the tool name and title. It fails to state what the tool actually does, such as returning the number of days in the month of the given date, and provides no differentiation from siblings like x402-days-in-month-year or x402-month-days.

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 guidance on when to use this tool versus alternatives such as x402-days-in-month-year or x402-days-in-quarter. The description offers no context about acceptable inputs, expected results, or why an agent would select this specific tool.

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