usefulapi

Lob MCP server. Verify US & international addresses and send physical mail (postcards, letters, checks) via Lob.

Claude

Open Settings → Connectors → Add custom connector
Paste this URL:
https://lob.usefulapi.io/mcp
Authenticate with Lob when prompted

Cursor · VS Code · Windsurf · Cline

Add to your MCP config, then reload & authorize:

{
  "mcpServers": {
    "lob": {
      "url": "https://lob.usefulapi.io/mcp"
    }
  }
}

live20 toolsFree 100 tool calls / monthPro $9/mo · $90/yr

Tools 20

Tool	Type	What it does
`lob_verify_us_address`	read	Verify a US address Validate & standardize a US address, returning deliverability, corrected components, and a confidence score.
`lob_verify_intl_address`	read	Verify an international address Validate & standardize a non-US address. `country` (2-letter ISO code) is required.
`lob_us_zip_lookup`	read	Look up a US ZIP code Return the cities and state associated with a US ZIP code. Non-mutating. Lob API: POST /v1/us_zip_lookups.
`lob_us_autocomplete`	read	Autocomplete a US address Suggest complete US addresses from a partial primary line — useful for address entry. Non-mutating.
`lob_list_postcards`	read	List postcards List sent/scheduled postcards, newest first. Lob API: GET /v1/postcards.
`lob_get_postcard`	read	Get a postcard Retrieve a single postcard by id, including status, PDF url, and expected delivery. Lob API: GET /v1/postcards/{id}.
`lob_list_letters`	read	List letters List sent/scheduled letters, newest first. Lob API: GET /v1/letters.
`lob_get_letter`	read	Get a letter Retrieve a single letter by id, including status, PDF url, and tracking. Lob API: GET /v1/letters/{id}.
`lob_list_checks`	read	List checks List sent/scheduled checks, newest first. Lob API: GET /v1/checks.
`lob_get_check`	read	Get a check Retrieve a single check by id, including amount, status, and check number. Lob API: GET /v1/checks/{id}.
`lob_list_self_mailers`	read	List self-mailers List sent/scheduled self-mailers, newest first. Lob API: GET /v1/self_mailers.
`lob_list_addresses`	read	List saved addresses List saved address records, newest first. Lob API: GET /v1/addresses.
`lob_get_address`	read	Get a saved address Retrieve a single saved address record by id. Lob API: GET /v1/addresses/{id}.
`lob_list_templates`	read	List templates List saved HTML templates usable as postcard/letter artwork. Lob API: GET /v1/templates.
`lob_create_address`	write	Save an address record Create a reusable saved address record (does NOT send any mail). Returns an address id (adr_…) usable as `to`/`from` in mail tools. Lob API: POST /v1/addresses.
`lob_create_postcard`	write	Send a postcard (COSTS MONEY) ⚠️ SENDS A REAL POSTCARD and charges your Lob account (use a test_ key to avoid real mail/charges).
`lob_create_letter`	write	Send a letter (COSTS MONEY) ⚠️ SENDS A REAL LETTER and charges your Lob account (use a test_ key to avoid real mail/charges).
`lob_cancel_postcard`	write	Cancel a scheduled postcard Cancel a postcard before its send_date so it is never mailed (and not billed). Fails if the send window has passed. Lob API: DELETE /v1/postcards/{id}.
`lob_usage_status`	meta	Usage status (free-tier meter) Report the caller's current free-tier usage this month: calls used, monthly limit, remaining, and whether the cap is reached. Read-only; does not count against the meter.
`lob_upgrade`	meta	Upgrade to Pro (unlimited) Subscribe to the Pro plan for UNLIMITED Lob tool calls (the free tier caps monthly usage). Choose monthly ($9/month) or yearly ($90/year — 2 months free) billing. Returns a Stripe Checkout link to open in your browser; after payment your account upgrades automatically. Read-only; does not count against the meter.

Pricing

Plan	Price	Limit
Free	$0	100 tool calls / month
Pro	$9/mo · $90/yr	Unlimited

This is a Model Context Protocol endpoint — meant to be connected from an AI client, not opened in a browser. An invalid_token response at the URL is the auth gate working as designed; clients authenticate automatically.