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

Annotations already mark the tool as read-only and non-destructive; the description adds value by disclosing the data source (RIR RDAP), the response format (JSON), and the $0.003 USDC cost via x402. It does not cover rate limits or failure modes, but for a single-parameter read-only lookup this is sufficient.

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 compact, front-loaded single line that packs the function, output fields, source, format, and price with no filler. Every clause contributes meaningful 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?

With one required parameter fully described in the schema and annotations covering the safety profile, the description supplies the remaining necessary context: returned fields, data source, response format, and cost. It does not detail output structure or error conditions, but that is not essential for such a simple lookup.

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 'ip' parameter as an IPv4 or IPv6 address at 100% coverage, so the baseline is 3. The description does not add extra parameter syntax, formatting constraints, or edge-case guidance beyond what the schema already provides.

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 states a specific lookup function: identifying who operates an IP address via RDAP, and lists the returned attributes (registry, network range, organization, country). This clearly distinguishes it from sibling tools like dns_lookup or threat_ip, despite the generic tool name 'ip'.

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 clearly implies the use case — determining the operator of a given IP address — which provides enough context to route an agent to this tool over DNS or threat-intel siblings. However, it does not explicitly name alternatives or state when not to use this tool.

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