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

With no annotations, the description carries the full burden, but it only mentions the computation and the default period. It does not disclose how input is supplied, what the output looks like, or how edge cases (e.g., insufficient data) are handled.

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 only two sentences, front-loaded with the core purpose. The 'SMA' prefix and expansion is slightly redundant with the tool name, but overall there is no wasted content.

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 tool with an empty schema and no output schema, the description leaves critical gaps: no input formatting, no return value description, and no differentiation from similar moving-average tools. The agent gets the concept but not enough detail to call it 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?

The input schema declares zero parameters, so the description is the only source of parameter meaning. It does add useful high-level semantics: provide values, optional period/window, default of 20. However, it fails to specify the actual parameter names or input structure, leaving an agent unable to construct a reliable invocation.

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 verb ('Calculate') and resource ('Simple Moving Average of a price series'), making the tool's function immediately clear. The name and description both make clear this is SMA specifically, which helps distinguish it from the nearby 'moving-average' and 'ema' siblings.

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?

The description gives invocation hints ('Provide values and optional period/window') but no guidance on when to prefer this tool over alternatives like x402-moving-average or x402-ema. There are no explicit exclusions or context-based selection criteria.

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