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ReferralHero MCP by usefulapi

io.usefulapi/referralhero in the official MCP registry. Endpoint https://referralhero.usefulapi.io/mcp. Source: github.com/m190/usefulapi-mcp.

The registry describes it as: Read ReferralHero campaigns, subscribers, referrals and rewards; add subscribers and points.

We read its 28 tools on 2026-11-01. Nothing in them matched our tool-poisoning rules. It also sets server instructions, text a client puts in front of the model on connect; those were read too.

A clean read means these rules found nothing, not that the server is harmless. A server can change its tools at any time, which is why the index reads it again every week.

Connect it

The endpoint answers MCP over HTTP; that is how we read it. Add it to your client:

Claude Code

claude mcp add --transport http referralhero https://referralhero.usefulapi.io/mcp

Cursor: ~/.cursor/mcp.json

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

VS Code

code --add-mcp '{"name":"referralhero","type":"http","url":"https://referralhero.usefulapi.io/mcp"}'

Some servers ask you to sign in the first time a client connects, or want a key from the people who run them; the server's own docs say which.

Let Claude Code check servers as it adds them

With the free lazaretto-guard plugin installed, when Claude Code adds a server for you or writes one into an MCP config, the plugin reads the server's tools first and asks you if one of our rules matches. Install it, restart Claude Code, then ask it to run the command above.

Install lazaretto-guard

claude plugin marketplace add jamesdfinance-dev/lazaretto-plugins
claude plugin install lazaretto-guard@lazaretto-plugins

Tools it advertises

referralhero_list_campaigns referralhero_get_leaderboard referralhero_list_campaign_rewards referralhero_create_campaign referralhero_list_subscribers referralhero_get_subscriber referralhero_get_subscriber_by_email referralhero_get_subscriber_by_referral_code referralhero_search_subscribers_by_name referralhero_list_referrals referralhero_list_unlocked_rewards referralhero_list_subscriber_rewards referralhero_list_coupon_groups referralhero_get_coupon_group referralhero_add_subscriber referralhero_update_subscriber referralhero_delete_subscriber referralhero_add_points referralhero_track_transaction referralhero_confirm_referral referralhero_track_conversion_event referralhero_qualify_referral referralhero_unqualify_referral referralhero_promote_subscriber referralhero_unlock_promoted_reward referralhero_update_reward_status referralhero_create_coupon_group referralhero_add_coupons

Tool changes

We compare every full read of this server with the one before. No change in what its tools say has been seen since we started keeping this record on 2026-10-30.

Fingerprint of its tools at our last full read (2026-11-01): 8e11bd4a1a16d24e. A client can hash the tools it is served the same way and compare; the full value and a hash per tool are in this page as JSON.

Run this server? Show the check in your README

The badge reflects the latest weekly read:

Markdown

[![MCP tool check](https://lazaretto.dev/mcp-registry/io-usefulapi-referralhero/badge.svg)](https://lazaretto.dev/mcp-registry/io-usefulapi-referralhero)

How this was checked

Lazaretto connects to the endpoint the way any MCP client does, asks the server to introduce itself and list its tools, and reads every name, description, parameter schema and server instruction for tool poisoning: hidden directive blocks, orders to read local secrets, parameters built to carry secrets or the conversation out, orders that redirect another server's tools, and invisible characters. It never calls a tool. What we found across the registry.

To run the same check every time Claude Code adds a server, install the free lazaretto-guard plugin. Browse every server in the index.