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

With no annotations, the description carries the behavior disclosure burden, and it does state the core behavior: input is an array, output is an array of unique values, and order is preserved. It does not mention input mutation, type restrictions, or failure behavior, but for a simple pure array transformation the important behavioral traits are covered.

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 two short clauses with the operation named first and the output guarantee immediately after. Every word adds meaning; there is no redundant filler.

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 transformation, the semantic contract (input array -> ordered unique array) is mostly present, and it is complete enough if the 'Provide values' convention is understood. However, with no annotations, an empty input schema, and no output schema, the invocation mechanics remain underspecified, and overlap with sibling deduplication tools is not addressed.

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 schema defines no properties, and the 0-parameter baseline would normally be 4, but the instruction 'Provide values' implies an input that the schema does not expose, leaving the agent to guess how to pass the array. The description adds the concept of values and arrays but not enough to reconcile the empty 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?

The description uses a specific verb ('Remove duplicate values') and names the resource ('an array'), and it adds the important guarantee that unique elements keep their original order. It is clear about what the tool does, though it does not distinguish it from near-identical siblings such as x402-remove-duplicates and x402-unique-array.

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 guidance is given about when to prefer this tool over alternatives; the sibling list contains x402-remove-duplicates, x402-unique-array, and x402-unique-count, which appear to cover the same operation. Without an exclusion or routing hint, an agent cannot reliably choose among them.

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