passive_dns_lookup

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

No annotations are provided, so the description bears full responsibility for behavioral disclosure. It only describes the query action and output, but does not mention authentication requirements, rate limits, data freshness, or whether the operation is read-only. This is insufficient for a tool making external API calls.

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 extremely concise: two sentences plus a one-line argument description. Every sentence adds value. No redundant information. Front-loaded with the core purpose.

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?

Given the tool has a simple single parameter and an output schema exists (as indicated by context signals), the description provides sufficient context about input and output (historical resolutions). It does not mention pagination or limits, but for a lookup tool this is acceptable. The sibling context is not necessary for completeness here.

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 description adds meaningful semantic details to the sole parameter, clarifying that it accepts IPv4, IPv6, or domain names. Schema description coverage is 0%, so this justification is crucial. It could be enhanced by specifying expected format (e.g., no protocol prefixes) but is adequate.

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 clearly states it queries CIRCL Passive DNS for historical DNS resolutions, and specifies the two possible directions (hostnames to IP or IP to hostnames). This distinguishes it from sibling tools like check_ip_reputation or shodan_host_lookup which serve different purposes.

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 implies usage when historical DNS resolution data is needed, but does not explicitly state when to use this tool over alternatives like 'check_ip_reputation' or 'get_domain_intel'. No when-not-to-use guidance is provided.

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