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The Hunter MCP server is the official integration that connects your Caylex AI agents to Hunter’s B2B data platform, enabling programmatic access to email verification, contact enrichment, company insights, and domain-based email discovery. Through this server, AI agents can find and verify professional email addresses, enrich contact and company profiles, discover emails associated with a domain, and manage leads and outreach sequences — all without manual lookups or custom API wiring. Hunter’s API (v2) returns structured JSON responses covering contact data, deliverability checks, and company information sourced from Hunter’s proprietary index. This server is well-suited for AI-driven go-to-market workflows, sales prospecting automation, and any agent that needs reliable B2B contact data on demand.
Prerequisites:
  • A Hunter account is required — sign up at hunter.io to obtain a free API key from the Hunter dashboard.
  • Your Hunter API key must be generated and available before connecting this server in Caylex; keys can be retrieved, regenerated, or deleted from the Hunter API keys dashboard.
  • Access to certain features such as Leads, Leads Lists, Email Sequences, and Enrichment may depend on your Hunter plan tier — verify your plan supports the tools your agents need.
Important API details:
  • Authentication requires a Hunter API key, which must be provided via the api_key query parameter, the X-API-KEY header, or as a Bearer token in the Authorization header.
  • A special test API key (test-api-key) is available for validating requests on the Domain Search, Email Finder, and Email Verifier endpoints — it always returns dummy data and is useful for testing your Caylex setup.
  • API responses follow a consistent structure: a ‘data’ object with the requested content, a ‘meta’ object with request metadata, and an ‘errors’ array if the request fails.
  • Standard HTTP status codes are used: 200 for success, 201 for resource creation, 204 for no content, and 400 for bad requests — errors include descriptive messages to help diagnose failures.

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Server Details

PropertyValue
TransportStreamable HTTP
Server TypeExternal
Endpointhttps://mcp.hunter.io/mcp

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Authentication

This server supports the following authentication method:

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Header Authentication

This server authenticates via HTTP headers. During the server onboarding flow, you will be prompted to confirm the required headers. Note that you do not provide the values for the headers during the server on-boarding. Header values are provided by the users during the Auth Link flow.

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Getting Started

1

Add the server

Navigate to the Server Library and click on the New Server button. Find Hunter in the Caylex Catalog.
2

Server Onboarding flow

Go through the server onboarding flow.
3

Use in a project

Add the server to a project by configuring project connections. Its tools are now available to any agents connected to that project.
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Dropcontact

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LinkedIn Research

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Coresignal

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References

https://hunter.io/blog/hunter-mcp-server-bringing-ai-and-b2b-data-together/

https://hunter.io/api-documentation