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dns-doctor

by dev.dnsdoctor

check_reverse_dns

Read-onlyIdempotent

Check one sending IP's forward-confirmed reverse DNS (FCrDNS): reads the IP's PTR record, then resolves that hostname back and reports whether it returns to the same IP. verdict is confirmed (the pair agrees — what receivers want to see), ptr_missing (the IP publishes no reverse record), or mismatch (a PTR that does not resolve back). A PTR on its own proves nothing, because the IP's operator writes its own reverse zone — only the forward confirmation is evidence, so never report a bare PTR as verified. The fix is always made by whoever controls the IP (the hosting or mail provider), never in the sending domain's own DNS. Pass a public IPv4 or IPv6 address.

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
ipYesThe sending IP to check, IPv4 or IPv6. Must be a public address — private, loopback and CGNAT ranges have no meaningful reverse DNS and are refused.

Output Schema

TableJSON Schema
NameRequiredDescriptionDefault

No arguments

TDQS

A4.5/5.0
Behavior5/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Beyond the annotations (readOnly, idempotent, non-destructive), the description explains the internal two-step resolution process, defines each verdict, and warns about the misleading nature of bare PTR records. This provides rich behavioral context that annotations alone do not capture.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Every sentence in the description adds value: purpose, verdict definitions, critical warning about PTR interpretation, fix responsibility, and input requirement. It is front-loaded with the core purpose and remains compact without redundancy.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given the simple one-parameter schema, rich annotations, and existing output schema, the description fully covers what the tool does, how to interpret its output, and the operational context (who can fix issues). No significant gaps remain.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

The schema already covers the single 'ip' parameter with full description including the public address requirement. The description repeats the constraint ('Pass a public IPv4 or IPv6 address') but adds no additional semantic meaning beyond what the schema already provides. Baseline 3 applies due to 100% schema coverage.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description uses a specific verb ('Check') and resource ('forward-confirmed reverse DNS'), explaining the exact mechanism (PTR lookup then forward resolution) and the three possible verdicts. This clearly distinguishes it from sibling tools like check_record or check_dkim_selector.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines4/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description gives clear context for when to use the tool (checking a sending IP's FCrDNS) and crucial guidance on interpreting results ('never report a bare PTR as verified'), plus where fixes belong. It does not explicitly name alternative tools for comparison, but the usage context is unambiguous.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

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TDQS

A4.4/5.0
Disambiguation5/5

Each tool targets a distinct DNS or email authentication task. Despite multiple DMARC-related tools, their purposes are clearly differentiated: build_dmarc_upgrade upgrades policies, generate_dmarc_record creates new ones, validate_dmarc_record validates pasted records, and scan_domain vs get_report differentiate fresh vs cached scans.

Naming Consistency5/5

All tool names follow a consistent verb_noun pattern in snake_case (e.g., build_dmarc_upgrade, check_record, scan_domain). No mixing of naming conventions, making the set predictable and easy to navigate.

Tool Count5/5

With 11 tools, the server is well-scoped for a DNS/email authentication diagnostics tool. The number covers essential operations without being overwhelming or sparse.

Completeness4/5

The tool set covers core workflows: DMARC management (generate, validate, upgrade, parse reports), DNS checks (propagation, reverse DNS, SPF lookups), and DKIM selector checks. Minor gaps exist, such as the absence of SPF validation or DKIM signature verification, but the main diagnostic and monitoring use cases are supported.

Resources