CLI

demo

npx mcp-failure-lab demo

Runs the built-in deterministic delay scenario through the real execution path.

serve

npx mcp-failure-lab serve

Starts the MCP server over stdio and waits for a client.

run

npm run dev -- run examples/scenarios/delay-success.json
npm run dev -- run examples/scenarios/delay-success.json --report json

The current run command uses the built-in Failure Lab server. It does not orchestrate an external MCP host.

Reporting

Console is the default. Pass --report json for machine-readable scenario results and command errors.

Exit codes

Code	Meaning
0	All expectations passed
2	Scenario ran, but one or more assertions failed
1	Scenario could not be loaded or executed

JSON command error codes are invalid_arguments, scenario_load_failed, and scenario_execution_failed.