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Precoro MCP by usefulapi
io.usefulapi/precoro in the official MCP registry.
Endpoint https://precoro.usefulapi.io/mcp. Source: github.com/m190/usefulapi-mcp.
The registry describes it as: Read Precoro purchase orders, invoices, suppliers and budgets; approve, reject and submit documents.
We read its 24 tools on 2026-10-31. 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 mcp add --transport http precoro https://precoro.usefulapi.io/mcp{
"mcpServers": {
"precoro": {
"url": "https://precoro.usefulapi.io/mcp"
}
}
}code --add-mcp '{"name":"precoro","type":"http","url":"https://precoro.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.
claude plugin marketplace add jamesdfinance-dev/lazaretto-plugins
claude plugin install lazaretto-guard@lazaretto-pluginsTools it advertises
precoro_list_purchase_orders precoro_get_purchase_order precoro_list_purchase_requisitions precoro_get_purchase_requisition precoro_list_invoices precoro_get_invoice precoro_list_expenses precoro_get_expense precoro_list_receipts precoro_get_receipt precoro_list_payments precoro_list_budgets precoro_list_contracts precoro_list_ap_inbox precoro_list_suppliers precoro_get_supplier precoro_list_items precoro_get_item precoro_list_reference_data precoro_approve_document precoro_reject_document precoro_submit_document precoro_create_purchase_requisition precoro_create_supplier
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 (2026-10-31):
058f30e9bf067a8f. 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:
[](https://lazaretto.dev/mcp-registry/io-usefulapi-precoro)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.