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

Beyond the readOnlyHint and destructiveHint annotations, the description discloses the kinds of data returned and the non-obvious cost of the call ('Spends 1 credit'). This gives the agent useful expectations about both the result content and the side effect of consuming a credit.

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 a single efficient sentence with no filler. It front-loads the core operation, then adds the return categories and cost. Every phrase contributes useful information.

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 IP lookup with an output schema present, the description adequately covers the operation, the kind of results returned, and the credit cost. Nothing essential is missing for an agent to invoke it 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%: the single 'ip' parameter is already documented as 'IPv4 or IPv6 address.' The tool description reinforces the parameter's role but does not need to add further detail. The baseline of 3 is appropriate because the schema already carries the semantic weight.

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 opens with a specific verb and resource, 'Look up an IP address,' and then enumerates concrete result categories: geolocation, connection type, proxy/VPN/Tor/datacenter flags, and fraud/risk score. This clearly differentiates it from sibling tools that handle phone/email verification or account/bulk operations.

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 intended use is clear from the resource itself: use it when an IP address needs enrichment or risk scoring. It does not explicitly list alternatives or exclusions, but the sibling set contains no competing IP-specific tool, so an agent can route to this tool without ambiguity. Mentioning that it 'Spends 1 credit' adds practical usage context.

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