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

With no annotations, the description carries the full behavioral burden. It does disclose one valuable edge case ('returning zeros when the deviation is zero') and the free-trial/pricing context, but says nothing about input encoding expectations, output shape, or error behavior for non-numeric input.

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 short sentences, front-loaded with the operation and followed by the zero-deviation edge case, with no padding. The emoji pricing tag is minor noise but not disruptive.

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 1-parameter numeric utility with no output schema, the description should at least clarify the input string format and what the standardized output looks like. The zero-deviation case is covered, but the input-encoding ambiguity and missing output description leave an agent unable to call it confidently.

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?

There is a single parameter, 'values', typed as string with 0% schema description coverage. The description says 'an array' but never explains the expected encoding (comma-separated? JSON string?), which is precisely the ambiguity the schema leaves unresolved. It adds little beyond the schema.

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 operation (standardize to zero mean and unit variance) with the resource (an array), which is clearer than the tautological name. However, it does not differentiate itself from the many near-identical siblings such as x402-standardize, x402-standardize-array, x402-normalize-array, and x402-zscore-array, leaving the agent unable to tell them apart.

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 when-to-use guidance, no statement of when another normalization tool is preferable, and no prerequisites. With such a dense sibling cluster of standardize/normalize/zscore variants, the absence of any routing guidance is a real gap.

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