spf_checkCheck if a domain has a valid SPF (Sender Policy Framework) DNS record. SPF specifies which mail servers are authorized to send email on behalf of a domain.
| Name | Required | Description | Default |
|---|---|---|---|
| domain_name | Yes | The domain to check SPF records for, e.g. example.com |
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint, openWorldHint, idempotentHint, and destructiveHint=false, covering the safety profile. The description adds a definition of SPF and the concept of 'valid', but does not disclose what happens when no SPF record exists, the return format, or any operational behavior like rate limits.
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 exceptionally concise: two sentences that front-load the action and resource, followed by a brief definition of SPF. Every word earns its place, with no redundancy or 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?
Given the tool's simplicity and the rich annotations, the description is adequate but not complete. It lacks differentiation from sibling DNS tools and does not explain what 'valid' means in terms of return values or edge cases (e.g., no SPF record). For an agent selecting among many similar tools, this is a notable gap.
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 fully documents the single domain_name parameter with an example, achieving 100% schema description coverage. The description itself adds no further parameter semantics, so 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?
The description clearly states the tool checks if a domain has a valid SPF DNS record, using the specific verb 'Check' and a distinct resource (SPF). It is implicitly distinguished from sibling tools by focusing solely on SPF, but does not explicitly name alternatives.
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?
No guidance is provided on when to use this tool versus other DNS checks like dkim_check or dmarc_check. The description lacks any context, prerequisites, or exclusions, leaving the agent to infer usage solely from the tool name.
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.