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Ampworth calculators
com.ampworth/calculators in the official MCP registry.
Endpoint https://ampworth.com/mcp/calculators.
The registry describes it as: UK solar PV and heat pump calculators that follow the published MCS methods. Open, no key.
We read its 12 tools on 2026-10-26. 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
connection_route heat_pump_noise heat_pump_running_cost heat_pump_size hot_water_cylinder list_calculators radiator_flow_temperature room_heat_loss solar_pv_output solar_pv_self_consumption solar_pv_shading solar_pv_system_size
Run this server? Show the check in your README
The badge reflects the latest weekly read: 
[](https://lazaretto.dev/mcp-registry/com-ampworth-calculators)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.