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When I Work MCP by usefulapi
io.usefulapi/when-i-work in the official MCP registry.
Endpoint https://when-i-work.usefulapi.io/mcp. Source: github.com/m190/usefulapi-mcp.
The registry describes it as: Check shifts, time clock entries, time-off requests, swaps and availability, and manage shifts.
We read its 21 tools on 2026-10-21. 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
wheniwork_get_account wheniwork_list_users wheniwork_get_user wheniwork_list_locations wheniwork_list_positions wheniwork_list_shifts wheniwork_get_shift wheniwork_list_eligible_users_for_shift wheniwork_list_times wheniwork_list_time_off_requests wheniwork_get_time_off_request wheniwork_list_time_off_types wheniwork_list_shift_swaps wheniwork_list_availability wheniwork_list_annotations wheniwork_create_shift wheniwork_update_shift wheniwork_publish_shifts wheniwork_unpublish_shifts wheniwork_create_time_off_request wheniwork_update_time_off_request
Run this server? Show the check in your README
The badge reflects the latest weekly read: 
[](https://lazaretto.dev/mcp-registry/io-usefulapi-when-i-work)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.