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DERATE — truck fault codes
app.derate/derate in the official MCP registry.
Endpoint https://derate.app/mcp.
The registry describes it as: Heavy-duty truck SPN/FMI and OBD fault codes: meaning, safe-to-drive verdict, parts and recalls.
We read its 15 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
buscar_codigo es_seguro_manejar retiros_de_camion get_data_notes search_guides get_guide get_truck_fault_code interpret_derate search_fault_code_library list_supported_engine_families get_pricing get_download_links get_diagnosis list_fault_codes explain_fault_code
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The badge reflects the latest weekly read: 
[](https://lazaretto.dev/mcp-registry/app-derate-derate)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.