dmarc_checkCheck if a domain has a valid DMARC (Domain-based Message Authentication, Reporting & Conformance) DNS record. DMARC tells receiving servers what to do with emails that fail SPF or DKIM checks.
| Name | Required | Description | Default |
|---|---|---|---|
| domain_name | Yes | The domain to check DMARC records for, e.g. example.com |
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is covered. The description adds a semantic context (DMARC's effect on email handling) but does not disclose behavioral specifics like checking the _dmarc subdomain or what 'valid' entails. 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?
Two sentences: the first states the tool's purpose, the second gives background context. No redundancy, filler, or inaccessible information. It is concise and front-loaded.
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 simple read-only DNS lookup tool with a single parameter and no output schema, the description is fairly complete. It explains what the tool does and why DMARC matters. A perfect score would require explicit mention of validation criteria or the _dmarc prefix, but these are not essential for basic usage.
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?
Schema description coverage is 100% — the single parameter domain_name is clearly documented with an example. The tool description adds no additional parameter-specific meaning beyond that, 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 states a specific action and resource: 'Check if a domain has a valid DMARC ... DNS record.' This clearly distinguishes it from sibling tools like dkim_check, spf_check, or dns_lookup. It also adds helpful domain context about what DMARC does.
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 implicit usage context by explaining DMARC's role in email authentication, but it does not explicitly state when to use this tool versus alternatives (e.g., when to use dmarc_generate or spf_check). No exclusions or alternatives are mentioned.
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 has a specific purpose, but dns_lookup overlaps with cname/mx/ptr/txt lookups since it returns all record types. The 'check' tools validate records while 'lookup' tools merely retrieve them, which helps differentiate, but an agent could still confuse e.g., txt_lookup with dkim_check.
Naming follows a noun_action pattern (e.g., bimi_check, mx_lookup) but uses inconsistent actions: check, lookup, finder, and generate. 'imap_finder' and 'smtp_finder' break the noun_verb pattern, and there is no uniform verb choice.
With 16 tools, the count is at the upper edge of reasonable for an email deliverability domain. The individual DNS checks and server tests are justified, but some consolidation (e.g., a single lookup tool with record type parameter) could reduce redundancy.
Covers critical authentication checks (SPF, DKIM, DMARC, BIMI), blacklist checks, DNS lookups, and SMTP/IMAP connection tests. Missing DKIM generation and deeper reputation tools, but core deliverability verification is well-covered.