AtomicAPIs MCP Server

A Model Context Protocol (MCP) server that exposes 17 production-grade micro-API tools for AI assistants. Built with .NET 9 and the official ModelContextProtocol SDK.

MCP allows AI assistants like Claude to invoke these tools natively during conversation — no HTTP requests, API keys, or boilerplate needed on the client side.

Quick Install

One-click for Claude Desktop

Add this to your claude_desktop_config.json:

{
  "mcpServers": {
    "atomicapis": {
      "command": "dotnet",
      "args": ["run", "--project", "/path/to/atomicapis-mcp-server/src"]
    }
  }
}

One-click for Claude Code

claude mcp add atomicapis -- dotnet run --project /path/to/atomicapis-mcp-server/src

One-click for Kiro

Tools

Tool	Method	Description
WebToMarkdownTools	ExtractMarkdown	Scrape any URL and convert the page to clean Markdown. Strips nav, footer, scripts, and non-essential HTML to minimize tokens. SSRF-protected with a 5MB page limit.
EmailShieldTools	VerifyEmail	Check if an email address is disposable or from a known burner domain. Validates format, checks against a curated domain list, and verifies MX records via DNS.
TimezoneTools	ResolveTimezone	Convert latitude/longitude to full timezone data including IANA timezone, UTC offset, DST status, current local time, and next transition.
SchemaSniffTools	InferSchema	Auto-detect the format (JSON, CSV, XML) of a payload and infer its schema — field names, types, nullability, and nesting.
ProductSchemaTools	GenerateProductSchema	Generate JSON-LD Product structured data for SEO. Outputs both raw JSON-LD and a ready-to-embed <script> tag.
CsvSurgeonTools	CleanCsv	Clean, normalize, and deduplicate CSV data. Fixes encoding, normalizes headers, collapses whitespace, pads/truncates rows, and optionally normalizes date formats.
UtmLinkTools	CloakLink	Create cloaked UTM-tagged tracking URLs. Encode campaign parameters into a short token and decode them back.
JsonRepairTools	RepairJson	Fix broken JSON from LLM outputs — trailing commas, unquoted keys, single quotes, missing brackets. Optionally validate against a JSON schema.
TokenCounterTools	CountTokens	Count tokens for multiple LLM models (GPT-4, Claude, Llama, Mistral, Gemini). Estimates costs, context window usage, and flags when text exceeds the model's limit.
EmailAuthGraderTools	GradeEmailAuth	Audit a domain's email authentication setup: SPF, DKIM, DMARC, MTA-STS, and BIMI. Returns a letter grade (A–F), score, and actionable recommendations.
PiiRedactorTools	RedactPii	Detect and redact personally identifiable information from text. Handles emails, SSNs, credit cards, phone numbers, IP addresses, street addresses, dates of birth, and URLs.
PhoneValidatorTools	ValidatePhone	Validate international phone numbers across 30+ countries. Returns E.164 format, country info, number type (mobile/landline), and formatted output.
TaxIdValidatorTools	ValidateTaxId	Validate VAT and Tax IDs for EU, US, UK, Australia, and India. EU VAT numbers are verified against the VIES service when available.
PromptInjectionTools	DetectPromptInjection	Score text for prompt injection and jailbreak attempts. Uses pattern matching and heuristic analysis across multiple attack categories. Returns a risk score (0–100) with flagged spans.
SemanticSearchTools	SemanticSearch	Match a search query against a catalog of items using TF-IDF similarity. Supports fuzzy matching, synonym expansion, and configurable title weighting.
RelatedContentTools	FindRelatedContent	Find related content items from a corpus using TF-IDF and Jaccard similarity. Configurable thresholds, category boosting, and optional score breakdowns.
VoiceTaskParserTools	ParseTasks	Extract actionable tasks from voice transcripts. Identifies action verbs, assignees, priorities, deadlines, and confidence scores. Handles up to 100,000 characters.

Getting Started

Prerequisites

• .NET 9 SDK

Build

cd src
dotnet build

Run

cd src
dotnet run

The server communicates over stdio using the MCP JSON-RPC protocol. It is designed to be launched by an MCP-compatible client (e.g., Claude Desktop, Claude Code, Kiro, or any MCP host). See Quick Install above for configuration.

Architecture

src/
├── Program.cs              # MCP server entry point (stdio transport)
├── Tools/                  # MCP tool definitions (17 tools)
│   ├── WebToMarkdownTools.cs
│   ├── EmailShieldTools.cs
│   ├── TimezoneTools.cs
│   └── ...
└── Engines/                # Core logic (pure computation, no HTTP/DI concerns)
    ├── CsvCleaner.cs
    ├── SchemaInferrer.cs
    ├── EmailValidator.cs
    └── ...

Tools define the MCP interface — parameter descriptions, validation, and response formatting. Each tool delegates to an Engine class that contains the pure business logic with no framework dependencies.

Dependencies

Package	Version	Purpose
ModelContextProtocol	1.1.0	MCP SDK for .NET
Microsoft.Extensions.Hosting	9.0.6	Host builder for DI and lifecycle
HtmlAgilityPack	1.12.4	HTML parsing (Web-to-Markdown)
ReverseMarkdown	5.2.0	HTML-to-Markdown conversion
GeoTimeZone	6.1.0	Coordinate-to-timezone lookup
DnsClient	1.8.0	DNS queries (email auth grading)

License

MIT