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Service Fusion MCP by usefulapi

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

The registry describes it as: Read Service Fusion customers, jobs, estimates, invoices and schedule; create customers and jobs.

We read its 26 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 service-fusion https://service-fusion.usefulapi.io/mcp

Cursor: ~/.cursor/mcp.json

{
  "mcpServers": {
    "service-fusion": {
      "url": "https://service-fusion.usefulapi.io/mcp"
    }
  }
}

VS Code

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

servicefusion_get_me servicefusion_list_customers servicefusion_get_customer servicefusion_list_customer_equipment servicefusion_get_customer_equipment servicefusion_list_jobs servicefusion_get_job servicefusion_list_estimates servicefusion_get_estimate servicefusion_list_invoices servicefusion_get_invoice servicefusion_list_calendar_tasks servicefusion_get_calendar_task servicefusion_get_availability servicefusion_list_techs servicefusion_get_tech servicefusion_list_tech_departments servicefusion_list_crews servicefusion_get_crew servicefusion_list_job_categories servicefusion_list_job_statuses servicefusion_list_payment_types servicefusion_list_sources servicefusion_create_customer servicefusion_create_job servicefusion_create_estimate

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): 02be8c2f5ae14af8. 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-service-fusion/badge.svg)](https://lazaretto.dev/mcp-registry/io-usefulapi-service-fusion)

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.