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Sendlane MCP by usefulapi

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

The registry describes it as: Manage Sendlane lists, contacts, tags and custom fields; read campaign and SMS reports.

We read its 31 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 sendlane https://sendlane.usefulapi.io/mcp

Cursor: ~/.cursor/mcp.json

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

VS Code

code --add-mcp '{"name":"sendlane","type":"http","url":"https://sendlane.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

sendlane_list_lists sendlane_get_list sendlane_list_list_contacts sendlane_list_list_unsubscribed sendlane_list_contacts sendlane_get_contact sendlane_list_unsubscribed_contacts sendlane_get_contact_subscriptions sendlane_get_contact_tags sendlane_get_contact_custom_fields sendlane_list_tags sendlane_get_tag sendlane_list_tag_contacts sendlane_list_custom_fields sendlane_list_segments sendlane_list_segment_contacts sendlane_list_campaigns sendlane_get_campaign sendlane_get_campaign_report sendlane_list_sms_messages sendlane_get_sms_report sendlane_list_sender_profiles sendlane_create_list sendlane_update_list sendlane_add_contacts_to_list sendlane_remove_contact_from_list sendlane_unsubscribe_contact sendlane_create_tag sendlane_add_contact_tags sendlane_remove_contact_tag sendlane_set_contact_custom_fields

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): c615511928c76951. 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-sendlane/badge.svg)](https://lazaretto.dev/mcp-registry/io-usefulapi-sendlane)

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.