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

No annotations are supplied, so the description carries the full behavioral burden. It does add real value by disclosing the default window of 3 and the monetization model ('5 free trial calls per signed wallet'), which tells the agent a quota applies. However, it says nothing about output length (presumably a reduced array of length n-window+1), handling of windows larger than the input, or null behavior.

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?

Two compact sentences, operation and default front-loaded, inputs listed, no filler. Every clause carries information.

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 simple two-parameter math tool with no output schema, the description covers the core operation, the default, and the billing/quota context. It stops short of stating the shape of the returned series or edge-case behavior, which matters because there is no output schema to fall back on.

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?

With 0% schema description coverage, the description must compensate, and it partially does by naming both inputs and giving the window default. But it describes values as an array while the schema types both parameters as strings, leaving the agent unsure of the expected wire format — a gap the description neither resolves nor acknowledges.

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 operation on a specific resource ('rolling sum over a numeric array with a fixed window') and gives the default window of 3, so an agent knows exactly what computation happens. It does not distinguish itself from closely related siblings such as x402-moving-average, x402-rolling-max/min, or x402-cumulative-sum, which leaves selection ambiguous in this very large tool family.

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 statement of when to use this instead of the ~20 statistically adjacent tools (rolling-max, rolling-min, moving-average, cumulative-sum, running-total). The only conditional information given is the default window value, which is parameter behavior, not usage guidance.

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