Free public API. Look up the DMARC record at _dmarc., parse policy/alignment/reporting tags, flag missing or too-permissive settings.
| Name | Required | Description | Default |
|---|---|---|---|
| domain | Yes | Domain to check DMARC for. |
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
The description discloses that this is a free public API and that it parses tags and flags missing or permissive settings, adding value beyond the read-only and open-world annotations. It does not contradict the annotations, and the safety profile is already covered.
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 very short at two sentences, but the first sentence 'Free public API.' provides marginal context and could have been integrated. The substantive sentence is dense and informative, so it's mostly concise.
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 single-parameter read-only tool with no output schema, the description covers the purpose, the method of lookup, and the analysis performed. This is sufficient for an agent to select and invoke the tool 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 single parameter 'domain' is fully described in the schema as 'Domain to check DMARC for.' The description adds meaning by specifying the lookup uses the _dmarc.<domain> convention, which goes beyond the schema and helps the agent understand the parameter's role.
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 looks up the DMARC record at _dmarc.<domain>, specifies it parses policy/alignment/reporting tags and flags issues. This specific verb+resource distinguishes it from sibling tools like DKIM and SPF checkers.
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 that this tool is for DMARC record checking, which is distinct from sibling tools for other DNS records. However, it does not explicitly mention when to use it over alternatives or offer exclusions, so it lacks the explicit when/when-not guidance for a 5.
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.
