fairquery-agent-trust-mcp

Official

by fairquery

Overview Schema Source Related Servers Discussions Admin

TypeScript

Hybrid

Check email syntax, typos, disposable & role (free)

email_check_syntax

Read-onlyIdempotent

Pre-filter signup or lead email lists offline by checking RFC-style syntax, normalizing addresses, and flagging typos, disposable, role, or free-provider domains before paid deliverability checks.

Instructions

WHAT: Offline email checks: RFC-style syntax + normalization, common domain typo "did you mean" (gmial.com -> gmail.com), disposable/temporary domain (bundled CC0 list, ~thousands of domains), role account (info@, sales@), free webmail provider. WHEN: Fast pre-filtering of signups or lead lists, before paying for email_validate_deliverability. WHEN NOT: Does NOT check DNS/MX - it cannot tell whether the domain receives mail (verdict is "invalid", "risky" or "unknown", never "valid"). Use email_validate_deliverability (paid) for MX/SPF/DMARC. COST: Free. Pure local function; no network, no token. RETURNS: Paged items: {type:"email_check",input,email,syntax_valid,local_part,domain,verdict(invalid|risky|unknown),reasons[INVALID_SYNTAX|DISPOSABLE_DOMAIN|ROLE_ACCOUNT|FREE_PROVIDER|POSSIBLE_TYPO|DNS_NOT_CHECKED],did_you_mean,is_disposable,is_role_account,is_free_provider,dns_checked:false}; meta.summary counts by verdict. EXAMPLE: {"emails":["someone@gmial.com"]} -> verdict "risky", reasons ["POSSIBLE_TYPO","DNS_NOT_CHECKED"], did_you_mean "someone@gmail.com".

Input Schema

TableJSON Schema

Name	Required	Description
`limit`	No	Page size: items to return, integer 1-1000 (default 100)
`emails`	Yes	Required. 1-10000 addresses (<= 320 chars each); "Name <addr>" and "mailto:" forms accepted. Example: ["jane@acme.com","bob@gmial.com"]
`offset`	No	Items to skip for paging, integer >= 0 (default 0); pass nextOffset from the previous response

Output Schema

TableJSON Schema

Name	Required	Description
`meta`	No	Tool-specific context (summary counts, cost notes, ...)
`count`	Yes	Number of items in this page
`items`	Yes	Result rows for this page
`total`	Yes	Total items before paging
`offset`	Yes	Offset of the first item in this page
`hasMore`	Yes	True if more items exist after this page
`nextOffset`	Yes	Offset to pass for the next page, or null

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.0Oct 17, 2026

TDQS

A4.4/5.0

Behavior4/5

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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint=false, and destructiveHint=false, so the safety profile is covered. The description adds genuinely non-structured context: it is a pure local function with no network and no token, it is free, and the verdict can never be 'valid' because DNS is not checked. That is useful behavioral disclosure, though it partly overlaps openWorldHint.

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 WHAT/WHEN/WHEN NOT/COST/RETURNS/EXAMPLE labeling is well front-loaded and skimmable. However, the RETURNS block enumerates the full response field list even though an output schema exists, which is mild redundancy against the conciseness goal.

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?

For a read-only local batch checker with an output schema present, everything an agent needs is supplied: scope, exclusions, cost, and verdict semantics. Nothing required to invoke it correctly is missing.

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?

Schema description coverage is 100%, so limit/offset/emails are already documented including accepted forms and paging. The description's EXAMPLE restates the input shape without adding format or semantic detail beyond the schema; baseline 3 applies.

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 WHAT line names a specific verb set and resource (offline email checks: syntax, typo, disposable, role, free provider) and explicitly frames scope as local/offline. It contrasts itself cleanly against the sibling email_validate_deliverability, so an agent can distinguish the two without opening either schema.

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

Usage Guidelines5/5

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

Explicit WHEN (fast pre-filtering of signups or lead lists, before paying for validation), WHEN NOT (no DNS/MX, verdicts never 'valid'), and a named alternative (email_validate_deliverability). Routing is fully determined.

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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