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

Annotations already establish readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is covered. The description adds practical context by naming the output categories and showing that a SEON license key is required via the example, with no contradiction of the annotation hints.

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 one focused, front-loaded sentence followed by a concrete invocation example. It contains no filler, and the example helps an agent immediately understand the expected call shape without adding unnecessary length.

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?

Because there is no output schema, the description appropriately compensates by enumerating the main returned data categories. Required and optional parameters are covered by the schema, and the example provides a valid invocation. The main omissions are rate-limit/error behavior, but these are secondary for a simple read-only lookup with strong annotation coverage.

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 100%, so the baseline is 3 and the schema fully documents phone, config, and _apiKey. The description's example repeats what the schema examples already show and does not add new meaning to the parameters, particularly for the optional config object.

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 ('Look up') and identifies a specific resource, phone numbers via SEON, with concrete result categories: carrier, line type, validity, and linked online/social/account platforms. The phrase 'digital footprint of a phone number' clearly distinguishes it from the seon_email, seon_ip, and seon_fraud 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 clear context: an agent should use this tool when it needs a phone number's SEON digital footprint, including carrier/line-type validation and linked platforms. It does not explicitly list alternatives or exclusion conditions, so it falls short of a 5, but the scope is unambiguous enough for correct selection.

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