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

With no annotations provided, the description carries the full burden, and it discloses little beyond the mathematical operation: no output shape, no behavior when the series is shorter than the window, no statement of whether the result is padded or truncated. The pricing note ('5 free trial calls per signed wallet') is the one piece of real behavioral context, implying a metered paywall and a signing requirement, but nothing else is disclosed.

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 with the operation front-loaded and the input requirement immediately after. The emoji and free-trial tagline are promotional noise that does not help invocation, though they cost little space.

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?

The tool has three parameters with zero schema documentation, no annotations, and no output schema, so the description is the only source of truth and it leaves the data format and the period/window distinction unexplained. For a computation tool whose caller must format a price series correctly, that gap is material.

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 all three parameters are typed merely as 'string', so the description must compensate. It clarifies that values is the input series and that period/window are optional with a default of 20, but it never explains the expected string encoding for values or why both 'period' and 'window' exist as separate parameters — a redundancy an agent cannot resolve from either source.

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 ('Calculate the Simple Moving Average (SMA) of a price series'), which is unambiguous about what it computes. However, the crowded sibling set contains x402-moving-average, x402-ema, x402-exponential-smoothing and x402-smma-like tools, and the description makes no attempt to distinguish SMA from those alternatives.

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 choose SMA over the sibling moving-average/EMA tools, nor on prerequisites such as minimum data length relative to the window. The only conditional information is a default period of 20 and a free-trial quota, neither of which is usage guidance in the selection sense.

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