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

No annotations are provided, so the description carries the full behavioral burden. The only behavioral detail is the pricing line ('5 free trial calls per signed wallet'), which hints at payment/auth context, but nothing is said about defaults, error behavior, or which inputs are tolerated for an unpinned, zero-required-parameter tool.

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?

Tight and front-loaded: the core behavior leads and the promotional trial note trails. It is appropriately sized for a trivial utility, though the emoji/pricing clause adds little functional value.

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 tool with no annotations, no output schema, and 0% schema coverage, the description should at minimum pin down input format and defaults. It leaves both undocumented, so an agent cannot reliably construct a call from the definition alone.

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 parameter is documented anywhere. The prose implies a month and a year input but says nothing about expected format (e.g. '2024' vs '24', '1' vs 'January') or what happens when they are omitted, since both are optional.

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?

States a specific verb and resource ('Returns the number of days in a given month of a given year'), so the agent knows exactly what it computes. However, it does not differentiate itself from near-identical siblings such as x402-days-in-month and x402-days-in-month-year, leaving the agent to guess which variant to call.

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 and no mention of the overlapping siblings (x402-days-in-month, x402-days-in-month-year). The description gives no conditions, prerequisites, or alternatives, so selection is left entirely to inference from the name.

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