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Fiken MCP by usefulapi

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

The registry describes it as: Read invoices, bills, contacts, ledger and bank balances; create drafts and contacts in Fiken.

We read its 31 tools on 2026-11-02. 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 about every two weeks.

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 fiken https://fiken.usefulapi.io/mcp

Cursor: ~/.cursor/mcp.json

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

VS Code

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

fiken_get_user fiken_list_companies fiken_get_company fiken_list_accounts fiken_get_account_balances fiken_list_bank_accounts fiken_get_bank_balances fiken_list_contacts fiken_get_contact fiken_list_invoices fiken_get_invoice fiken_list_invoice_drafts fiken_list_credit_notes fiken_list_offers fiken_list_order_confirmations fiken_list_products fiken_get_product fiken_list_sales fiken_get_sale fiken_list_purchases fiken_get_purchase fiken_list_journal_entries fiken_list_transactions fiken_list_projects fiken_list_time_entries fiken_list_inbox_documents fiken_create_contact fiken_create_product fiken_create_invoice_draft fiken_issue_invoice_from_draft fiken_send_invoice

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 (2026-11-02): 3a6d35dbb9591511. 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.

Rather than checking back: subscribe to this server's tool changes (a feed, no account and no address needed). Tool names and dates only, never what a tool says.

Run this server? Show the check in your README

The badge reflects the latest read:

Markdown

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

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.