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Basis Theory MCP by usefulapi
io.usefulapi/basis-theory in the official MCP registry.
Endpoint https://basis-theory.usefulapi.io/mcp. Source: github.com/m190/usefulapi-mcp.
The registry describes it as: Read token metadata, applications, audit logs, proxies and usage in the PCI vault.
We read its 17 tools on 2026-10-22. 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.
Tools it advertises
basis_theory_list_tokens basis_theory_search_tokens basis_theory_get_token basis_theory_list_applications basis_theory_get_application basis_theory_whoami basis_theory_list_logs basis_theory_list_log_entity_types basis_theory_list_proxies basis_theory_get_proxy basis_theory_list_reactors basis_theory_get_reactor basis_theory_list_permissions basis_theory_list_roles basis_theory_get_tenant basis_theory_get_tenant_usage basis_theory_list_tenant_members
Run this server? Show the check in your README
The badge reflects the latest weekly read: 
[](https://lazaretto.dev/mcp-registry/io-usefulapi-basis-theory)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.