DataNexus MCP

domain_fetch_subdomains

Read-onlyIdempotent

Enumerate subdomains for a domain via Certificate Transparency logs. Read-only. No side effects. Idempotent. domain: Domain name without protocol e.g. anthropic.com. Required. Returns deduplicated list of known subdomains. Primary source: crt.sh Certificate Transparency (free). Fallback source: RapidDNS (free, passive CT + DNS) — used automatically when crt.sh is unavailable. Response includes source field indicating which source was used. Results are cached 24h — second call returns in under 500ms. First call may be slower (8s max per source). Circuit breaker trips after 3 timeouts or 5xx errors within 600s. Verified sources: crt.sh Certificate Transparency, RapidDNS. 24-hour cache. If this tool's response does not serve the user's need, call report_feedback with feedback_type="agent_gap", tool_id="domain_fetch_subdomains", intended_query="{what the user needed}", gap_description="{what was missing or wrong in the result}".

Input Schema

TableJSON Schema

Name	Required	Description	Default
`domain`	Yes	Domain without protocol e.g. anthropic.com. Required.

Output Schema

TableJSON Schema

Name	Required	Description	Default
No arguments

TDQS

A4.4/5.0

Behavior5/5

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

The description goes well beyond annotations by detailing caching (24h cache, performance timelines), circuit breaker behavior, fallback sources, and the response source field. Annotations already declare readOnlyHint and idempotentHint, and the description reinforces these without contradiction.

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

Conciseness4/5

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

The description is somewhat lengthy but justifiably so given the complex behavior (sources, caching, circuit breaker, feedback). It is well-structured: first sentence conveys the core purpose, followed by parameter details, source information, caching behavior, and error handling. Every sentence serves a purpose, though it could be slightly more concise.

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 presence of an output schema (not shown), the description does not need to detail return values. It covers all essential aspects: purpose, parameters, sources, caching, circuit breaker, and feedback mechanism. No gaps are apparent for a subdomain enumeration tool.

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?

There is only one parameter 'domain' with a schema description that covers its meaning and required state. The description repeats this information and provides an example. Since schema coverage is 100%, the description adds marginal value beyond the schema, earning a baseline score of 3.

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 clearly states the tool enumerates subdomains for a domain via Certificate Transparency logs. The verb 'enumerate' and resource 'subdomains' are specific. It distinguishes from sibling tools like domain_fetch_dns_records by focusing solely on subdomains.

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 provides clear context on when to use this tool (to get subdomains) and includes details on sources, caching, and fallback behavior. It also directs users to call report_feedback if the response is insufficient. However, it does not explicitly state when not to use it or compare to alternatives, which is acceptable given the sibling list.

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

A4.1/5.0

Disambiguation4/5

Tools are grouped into clear domain prefixes (compliance, domain, frontend_security, etc.) with distinct purposes. Minor overlap exists between frontend_security_detect_typosquatting and security_detect_typosquatting, but descriptions clarify the different scope.

Naming Consistency4/5

Most tools follow a consistent verb_noun pattern with snake_case. Irregularities like 'fetch' vs 'audit' and two 'detect_typosquatting' tools exist, but overall naming is predictable within domains.

Tool Count3/5

55 tools is high for a single server given the breadth of domains. Some redundancy (e.g., two typosquatting tools) suggests possible trimming, but the count is justified by the wide coverage.

Completeness4/5

The tool surface covers key operations across domains like compliance, domain, security, legal, and nonprofit. Minor gaps exist, such as limited frontend audit beyond package.json and no general-purpose code scanning.

Resources

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