Run an overall email-deliverability health check for a domain by combining MX, SPF, DKIM, and DMARC signals into a graded summary with actionable findings.
Run an overall email-deliverability health check for a domain — combines MX, SPF, DKIM, DMARC and related signals into a single graded summary with actionable findings. 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 safe-read profile is covered. The description adds genuinely useful non-schema context: it is 'Free — no verification credits', which bears on cost-sensitive tool selection, and it discloses the return shape (a graded summary with findings). It does not mention rate limits or what happens on an unresolvable domain.
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 compact clauses with the aggregate purpose and scope front-loaded, followed by the cost note. Nothing is redundant and every clause earns its place.
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 tool with no output schema, the description covers what it does, what it aggregates, the rough return shape, and cost — enough to call it correctly. The grade scale and failure behavior for invalid domains are the only remaining gaps, and they are minor.
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?
There is a single required parameter whose schema description is fully covered ('The domain to inspect, e.g. example.com'). The prose adds no further semantics about the domain argument (e.g. subdomains, IDN, validation), so the schema carries the burden and the 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 and resource ('Run an overall email-deliverability health check for a domain') and makes clear it is an aggregate of MX, SPF, DKIM and DMARC. An agent can distinguish it from the sibling single-check tools (check_mx, check_spf, check_dmarc, check_dkim) without reading any schema.
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 phrase 'combines MX, SPF, DKIM, DMARC and related signals into a single graded summary' implies this is the one-shot aggregate to use instead of calling the individual check_* siblings, giving clear usage context. It stops short of an explicit 'use this instead of X when Y' routing statement or naming exclusions.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.