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

Annotations already cover the safety profile (readOnlyHint, openWorldHint, destructiveHint=false), so the bar is lower. The description adds one real behavioral nuance: RDAP/ASN is returned 'for each public address', implying multi-address results and that private addresses yield no such data. It says nothing about failure modes for unresolvable hostnames or rate limits, keeping this at a moderate score.

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?

A single front-loaded sentence that covers input and output with zero filler. Nothing here repeats structured fields verbatim.

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?

No output schema exists, so the description carries the return-value burden, and it does so adequately by naming the two returned artifacts. For a read-only one-parameter lookup, only error/timeout behavior is missing, which is a minor gap.

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?

With 0% schema description coverage, the description must define the lone 'target' parameter, and it does: a hostname or a literal IP address. It does not address edge cases like IPv6 literals, CIDR ranges, or URL schemes, but the core accepted input types are unambiguously stated.

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?

Names a specific verb pair (resolve a hostname / take an IP address) plus a concrete resource and the exact data returned (RDAP network data and ASN). It implicitly separates itself from lookup_domain_rdap by being the address-side counterpart, though it never names that sibling explicitly.

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?

Usage context is only implied: 'Resolve a hostname, or take an IP address directly' tells the agent it need not pre-resolve DNS itself. There is no explicit when-to-use/when-not guidance and no pointer to alternatives such as lookup_domain_rdap or check_ip_blacklists.

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