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

Annotations already declare readOnly, idempotent, non-destructive and open-world, so the safety profile is covered. The description adds genuinely new operational context beyond that: an explicit cost of 1 credit and the fact that data comes from RDAP delegated registry records, which tells the agent the source and authority of the answer. It stops short of covering invalid-input or unknown-IP behavior, which keeps it off a 5.

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?

One front-loaded sentence stating the ownership question and the returned fields, followed by an isolated cost tag. Every element earns its place and nothing is padded.

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 no output schema, the description correctly compensates by listing what comes back. For a one-parameter read-only tool with full annotation coverage this is nearly sufficient; only accepted input formats and error behavior are unaddressed.

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?

There is a single 'ip' parameter with 100% schema description coverage, so the schema is doing the documentation work. The description adds no format semantics such as whether IPv6 literals or hostnames are accepted, which would be the only meaningful gap to close here. Baseline 3 applies.

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 names a specific resource (an IP address) and the ownership question, and enumerates the returned fields: network name, range, country, organisations. That is much clearer than a title restatement, though it never distinguishes itself from the sibling rdap_lookup, which the parenthetical '(RDAP)' actively makes more confusable.

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?

There is no when-to-use guidance: no statement that this is for IPv4/IPv6 ownership or geolocation-of-network rather than domain reputation (domain_check) or registry object lookup (rdap_lookup). The agent must infer the selection rule from the tool name alone, and the RDAP mention muddies rather than clarifies the choice.

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