subfinder

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

With no annotations, the description carries the full burden and does a good job: it discloses passivity, lack of direct DNS queries, and undetectability. It could add more operational details such as runtime or rate limits, but it adequately communicates the key behavioral profile.

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 well-structured and front-loaded, but there is slight redundancy in emphasizing passivity both as 'Passive' and 'No direct DNS queries — completely passive and undetectable'. Overall, each sentence earns its place, though minor tightening is possible.

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 schema covers all parameters, the description explains the tool's behavior, use case, output, and key alternatives. No critical info is missing for an agent to invoke subfinder correctly.

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 input schema already provides 100% coverage of both parameters, including the example and the warning not to include subdomains. The description does not add significant new parameter-level meaning, but the schema is sufficient, so a baseline score of 3 is appropriate.

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 the action ('passive subdomain discovery'), the resource (target domain), and the method (multiple online sources). It also differentiates itself from sibling tools like dnsrecon and amass, making its purpose unambiguous.

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?

Explicitly says when to use the tool: initial domain reconnaissance to map external attack surface. It also names specific alternatives for related but different tasks: dnsrecon for active DNS brute-force/zone transfers and amass for deeper OSINT.

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