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API & MCP testing

API & MCP testing calls your MCP servers and HTTP endpoints from outside on a schedule, checks each answer against the assertions you set, and tracks uptime and latency from the runs. Tests are separate from Alerts: alerts watch the telemetry your services send, tests call your services. A test that goes down notifies you the way an alert does.

Two kinds of test

Section titled “Two kinds of test”
  • An MCP test probes your MCP server the way an agent would: it connects, can list the tools and can call one. A server that stops identifying itself, drops a tool or breaks a tool call fails the test instead of failing someone’s agent. If you ship an MCP server, this is its uptime monitoring. See MCP tests.
  • An HTTP test calls a URL with the method, headers and body you set, and checks the status, latency, headers and body that come back. See HTTP tests.

How it works

Section titled “How it works”

You create a test, in the app or by asking your agent, and the save runs it once; a test that fails that trial run is not saved. From then on it runs on its interval, every 30 seconds at the shortest. Each run passes, fails, errors, is rate limited or is missed, and a streak of failures turns the test Down while a streak of 429s turns it Rate limited. Uptime is the share of passing runs. Every state change sends a notification to the channels you chose. The rules are on Runs, states and uptime and Notifications.

Everything here is also available to an agent through Fixter’s MCP tools, from creating a test to reading its runs; see the API tests tools.

Where to go next

Section titled “Where to go next”