Free public API. Fetch a URL and return its response headers + security grade based on common security headers.
| Name | Required | Description | Default |
|---|---|---|---|
| url | Yes | Full URL with scheme, e.g. https://example.com. |
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnly, idempotent, and non-destructive. The description adds context about being a public API and outputting headers + security grade, but does not disclose potential network behavior, rate limits, or error handling. It does not contradict annotations.
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 a single sentence, concise and front-loaded with the core action. No filler or redundant information.
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 single parameter and lack of output schema, the description sufficiently explains what the tool does and what it returns (headers + security grade). It could mention return format or edge cases, but for the tool's simplicity it is reasonably complete.
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 provides full coverage of the single 'url' parameter with a clear description ('Full URL with scheme'). The tool description does not add any additional parameter semantics beyond the schema, so 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 clearly states the tool fetches a URL and returns response headers plus a security grade. This is a specific verb+resource (fetch URL) and distinguishes it from sibling tools like redirect_checker or website_status_checker.
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 context ('fetch a URL and return headers + security grade') but provides no explicit guidance on when to choose this over alternatives or any exclusions. The phrase 'Free public API' hints at accessibility but does not compare with siblings.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
Add one secure layer between your agents and this server.
Multiple tools operate in the same DNS/domain space, e.g., generic DNS record lookup overlaps with specific CNAME, TXT, SPF, DKIM, and DMARC lookups. Website status checker also overlaps with SSL check and redirect checker, though descriptions clarify their distinct purposes.
All tool names follow a consistent snake_case pattern with a 'tools_' prefix and an action word at the end (lookup, checker, check, finder). This makes the naming highly predictable and uniform.
16 tools is slightly above the ideal 3-15 range, but the domain intelligence scope is broad enough that each tool addresses a specific need without feeling bloated. The count is reasonable for a comprehensive domain/DNS toolkit.
The tool set covers a wide range of domain-related functionality: DNS records, email authentication (SPF, DKIM, DMARC), SSL/TLS, HTTP headers, redirects, WHOIS, availability, subdomain enumeration, and website status. No obvious critical gaps exist for its apparent purpose.
