Assess whether a domain (or the domain of an email address) can receive mail and how strong its sender authentication is. Returns MX presence, SPF and DMARC policy, whether it's a free consumer provider (gmail, etc.) or a known disposable/temp-mail provider, and an overall verdict. Use to qualify leads and flag throwaway signups.
| Name | Required | Description | Default |
|---|---|---|---|
| domain_or_email | Yes | A domain (stripe.com) or an email address (a@stripe.com) |
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations provided, the description carries full burden. It discloses the checks performed (MX, SPF, DMARC, provider detection) and that it returns a verdict. However, it omits details like whether external queries are made, rate limits, or authentication requirements. Adequate but not thorough.
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 two sentences long, front-loading the purpose in the first sentence. Every sentence adds value: purpose, return values, and use case. No unnecessary words.
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 single parameter and no output schema, the description adequately explains what it returns and when to use it. It does not specify output format or error handling, but for a simple assessment tool 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 input schema already has 100% coverage describing the parameter 'domain_or_email' as 'A domain (stripe.com) or an email address (a@stripe.com)'. The description does not add new semantic meaning beyond the schema, so baseline score of 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 assesses email deliverability and authentication for a domain or email, listing specific checks (MX, SPF, DMARC, free/disposable provider detection). This differentiates it from siblings like dns_lookup (general DNS) and domain_intel (WHOIS info).
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 explicitly advises using the tool to 'qualify leads and flag throwaway signups', providing clear context. It does not exclude alternative scenarios or compare directly with siblings, but the use case is well-defined.
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.
Each tool targets a distinct aspect of domain intelligence: DNS records, registration, combined report, email authentication, subdomains, and tech stack. There is no overlap; even the domain_report is a composite that doesn't conflict with individual tools.
All names use snake_case and are descriptive, but the pattern varies: some are noun_verb (dns_lookup), noun_noun (domain_intel, domain_report, email_deliverability, tech_stack), or single noun (subdomains). This is mostly consistent but not perfectly uniform.
Six tools is an ideal scope for a domain intelligence server. Each tool adds unique value without redundancy, covering registration, DNS, email, subdomains, tech stack, plus a combined report.
The tool set provides comprehensive coverage of domain intelligence: registration details, DNS records, subdomain discovery, email deliverability, and website technology fingerprinting. No obvious missing capabilities for typical lead qualification or research workflows.