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

With no annotations, the description carries the full burden. It does add useful operational context — the free-trial limit of 5 calls per signed wallet implies a payment/auth requirement and rate cap. However it says nothing about input parsing, error behavior, or what the result looks like, leaving meaningful gaps for a computation tool with zero annotation coverage.

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 functional sentence is front-loaded and tight. The trailing '🆓 5 free trial calls per signed wallet' is promotional padding, but it is brief enough not to obscure the core statement.

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?

No output schema, no annotations, and 0% parameter description coverage. An agent still does not know how to format the string array inputs in this case, so the description is not sufficient to invoke the tool correctly on its own.

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 coverage is 0%, so the description must compensate. It mentions 'actual and predicted arrays' and gives a useful default (predictors = 1), but the parameter is named 'predictors' while the prose says 'predicted', and it never explains that both params are strings or what encoding the arrays should use.

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 metric: 'Computes adjusted R-squared from actual and predicted arrays.' That is clear on its own, but it never distinguishes itself from the sibling x402-r-squared, so an agent cannot tell which of the two to pick from the text alone.

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 or when-not-to-use guidance, no prerequisites, and no mention of the closely related x402-r-squared tool that would be the obvious alternative. The only selection signal is the implicit 'adjusted' distinction in the name.

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