Connect Claude to the 1Lookup MCP server
Add one URL as a custom connector and Claude gets five 1Lookup tools for phone, email, and IP validation. Authorization runs over OAuth 2.1, so there is no API key to paste and nothing to install.
https://app.1lookup.io/api/mcpVerified in Claude and Cursor. Any client that supports remote MCP over streamable HTTP can add the same URL.
Four steps, one URL
The server is hosted, so nothing runs on your machine and there is no config file to edit.
- 01
Open Claude's connector settings
In Claude, go to Customize, then Connectors, then Add custom connector. On Team and Enterprise plans an owner adds it once in Organization settings, and members connect individually afterwards.
- 02
Paste the 1Lookup server URL
The URL is https://app.1lookup.io/api/mcp and that is the whole integration. There is no command to run, no package to install, and no API key or environment variable to fill in.
- 03
Approve the connection in your browser
Claude registers itself with the 1Lookup authorization server and opens a sign-in window. Sign in, review the access being requested, and approve. Claude receives a scoped token, not your API key.
- 04
Ask Claude to check something
The five tools appear in the client and Claude can call them mid-conversation. Each call bills to the 1Lookup plan you already have.
What to ask once it is connected
Claude decides when to call a tool, so you ask in plain language and it picks the right lookup.
- you ▸ Is +1 415 555 0132 a real mobile before we text it?
- you ▸ Verify j.ramos@acme.co and tell me if it is disposable.
- you ▸ Score the IP on this signup: 72.14.201.5
The five tools your agent gets
Each one is a single call Claude can make on its own. Three checks for phone, email, and IP, plus bulk for up to 50 values at a time and an account read so it can pace itself.
validate_phone
1 creditConfirms a number is real and active, and returns line type, carrier, DNC status, and a fraud score.
verify_email
1 creditChecks that an address exists and is deliverable, and flags disposable, role-based, and risky addresses.
ip_lookup
1 creditReturns geolocation and connection type, and flags proxy, VPN, Tor, and datacenter ranges.
bulk_verify
1 credit per recordValidates up to 50 phones, emails, or IPs in one call and returns a per-item result array.
get_account
FreeReturns the plan, subscription status, and remaining credit balance so an agent can pace itself.
What a tool call costs
Tool calls spend the same universal credits as the REST API. There is no separate MCP fee and no second bill to set up.
One credit per lookup
One credit per phone, email, or IP lookup, and one credit per record for bulk_verify. get_account is free, so an agent can check its balance before a large run without spending anything.
A paid plan is required
Programmatic access is a paid feature. A free-plan account receives HTTP 403 UPGRADE_REQUIRED on every tool call. A 7-day trial is available if you want to test the connection first.
Questions people actually ask
Cost, keys, plan requirements, and which clients can add the same URL.
Do I need a 1Lookup API key to use it in Claude?
No. The connection is authorized with OAuth 2.1: you sign in to 1Lookup in a browser window and approve access, and Claude receives a scoped token. There is no key to generate, paste, or rotate, and your API key never enters a prompt or a config file.
What does a 1Lookup tool call cost in Claude?
Claude bills you nothing extra; the cost is the 1Lookup credit the tool spends. One credit per phone, email, or IP lookup, one credit per record for bulk_verify, and get_account is free. Every paid tool says "Spends 1 credit" in the description Claude reads, so the cost is visible before it decides to call.
Does the free plan work with Claude?
No. Programmatic access is a paid feature, so every tool call from a free-plan account comes back as HTTP 403 UPGRADE_REQUIRED and Claude tells you an upgrade is needed rather than failing quietly. A 7-day trial covers testing the connection.
Which clients can add this URL?
Any client that supports remote MCP over streamable HTTP. We have verified the flow in Claude and Cursor. The server does not support SSE, so a client that only speaks the older SSE transport cannot connect.
Add it to Claude in about a minute
Paste the URL as a custom connector, approve the connection, and Claude can check any phone, email, or IP against the plan you already have.
https://app.1lookup.io/api/mcpProgrammatic access is a paid feature. A 7-day trial is available.