subdomain_enum

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

With no annotations, the description carries the burden of disclosing behavior. It says the tool is 'passive' and uses 'public sources', which implies read-only, non-intrusive behavior. It also reveals the output contains 'command and mode', indicating it runs a subprocess. However, it doesn't discuss potential side effects, rate limits, or reliance on third-party APIs, leaving some behavioral aspects opaque.

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 core description is a single, front-loaded sentence. The additional metadata block is structured and informative, though some entries (e.g., TOOL_NAME, DISPLAY_NAME) repeat the tool name and add little. The format is clear and scannable, but minor redundancy prevents a perfect score.

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?

For a one-parameter tool with an output schema, the description is quite complete. It covers purpose, use case, instructions, prerequisites, input semantics, output structure, and examples. It lacks explicit guidance on choosing this over sibling tools and does not mention error handling or edge cases, but overall it provides sufficient context for correct invocation.

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 only states 'domain' is a required string (0% coverage). The description adds meaningful semantics: 'Args: domain: Apex domain to enumerate (must be in scope).' It also provides an example 'example.com' and clarifies the domain should be an apex domain, which compensates well for the sparse schema.

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 tool's function: 'Discover subdomains of an in-scope domain (subfinder, passive).' It includes a specific verb ('discover'), a resource ('subdomains'), and scope ('in-scope domain'). While it doesn't explicitly differentiate from siblings like dns_recon, the mention of 'passive' and 'subfinder' conveys its unique approach.

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 provides clear context for when to use the tool via metadata: 'USECASE=Passively discover subdomains of an authorized domain from public sources', 'INSTRUCTIONS=1. Ensure domain is in scope, 2. Call with the apex domain', and 'PREREQUISITES=Domain authorized and in scope'. It gives situational guidance but does not explicitly contrast with alternatives (e.g., when to use dns_recon instead).

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