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

Annotations already establish that the tool is read-only, idempotent, and non-destructive. The description adds genuinely useful behavioral context beyond those annotations: it is a premium API with a specific cost ($0.25 USDC via x402) and it returns a defined set of data categories. No contradiction with annotations.

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 sentences with no filler: the first fronts the purpose and return categories, the second conveys the paid nature. Every clause adds selection or invocation value.

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 single-parameter, read-only lookup with rich annotations, the description is nearly complete: it names the input, the output categories, and the cost. It stops short of describing the exact response shape, but the listed profile categories give an agent enough expectation to invoke and interpret the result 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?

Schema description coverage is 100%, with the lookup parameter clearly documented as 'IPv4 or IPv6 address to profile' and an example provided. The tool description does not add parameter-level detail, but it does not need to because the schema already fully describes the only parameter.

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 ('Get'), names the resource ('comprehensive profile for an IP address'), and enumerates the key output categories (geolocation, ISP, organization, CIDR block, reputation assessment). This makes the tool's purpose unmistakable and distinguishes it from the many sibling profile tools aimed at other entity types.

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 makes the usage context clear: use it when you need a profile of an IP address. It does not explicitly name alternatives or state when-not-to-use, but the resource type is specific enough that no sibling tool is a true substitute, so explicit exclusions are not necessary.

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