Inspect a domain's DMARC policy and alignment to determine whether emails are protected against spoofing. Identify none, quarantine, or reject enforcement settings.
Check a domain's DMARC policy (none | quarantine | reject) and alignment. Free — no verification credits.
| Name | Required | Description | Default |
|---|---|---|---|
| domain | Yes | The domain to inspect, e.g. example.com |
Changes observed during successful MCP inspections.
v1.2.3Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered. The description contributes a genuinely new behavioral fact — 'Free — no verification credits' — which affects how an agent budgets calls, but says nothing about behavior when a domain has no DMARC record or about rate limits. Useful but thin beyond 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?
A single tight sentence that front-loads the action and resource, then appends the cost note. Every clause earns its place with no filler.
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 lookup with full schema coverage and no output schema, the definition is nearly sufficient: it names the tool, its target, its return domain, and its cost. The one meaningful gap is what happens when no DMARC record is published, which an agent would want to know before interpreting a result.
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?
Only one parameter exists and schema coverage is 100%, with the schema documenting 'domain' and giving an example. The description adds no syntax, normalization, or format guidance beyond that, so the schema is doing all the work. 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?
States a specific verb (check) and a specific resource (a domain's DMARC policy), and even enumerates the possible policy outcomes (none | quarantine | reject) plus alignment. This cleanly separates it from siblings like check_spf, check_dkim, and check_mx, which target different records.
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?
Usage is implied by the resource name and the note that it's free, but the description never says when to reach for this versus check_domain_health (which likely aggregates DMARC/SPF/MX) or how it fits a full domain audit. No exclusions or alternative routing are stated.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.