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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered. The description adds important behavioral context beyond annotations: a fixed per-call cost of $0.01 USDC and supported payment methods (x402 or credits), which affects invocation and budgeting.

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-load the returned data and then add the cost. Every sentence earns its place with no filler or redundancy.

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 one-parameter read-only lookup, the description covers the return values (network owner, range, country, reverse DNS) and the critical cost/payment behavior. With annotations covering safety and the schema covering the parameter, no essential context is missing.

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 fully documents the single required parameter 'ip' as an IPv4 or IPv6 address (100% coverage). The description adds no further parameter meaning, so the baseline of 3 is appropriate when the schema already carries the parameter burden.

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 title and description state a specific lookup resource (IP address) and enumerate the exact data returned: network owner, range, country, and reverse DNS. This clearly distinguishes it from siblings like lookup_domain_report and lookup_whois, though the description itself does not explicitly name alternatives or use a direct verb like 'retrieves'.

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 provides no guidance on when to use this tool versus lookup_dns, lookup_whois, or lookup_domain_report. It only states the cost, which is operational information rather than usage guidance.

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