Everything to test an MCP integration — in one place
Not a logger. Not a half-mock. A faithful MCP sandbox, a full trace viewer, error injection and your own servers — behind a single endpoint, with zero setup.
Full-fidelity trace viewer
Every tool call captured with arguments, response, latency and status — a LangSmith-style timeline built for MCP.
Error & latency injection
Flip a switch to return 429s, empty sets or slow responses and prove your agent recovers.
Latency you control
Simulate real-world response times to see how your agent paces itself.
Prompt diffing
Compare two system prompts across the same tool calls, side by side.
Stays in your sandbox
Nothing leaves to a third party. Mocked data is synthetic by design.
Bring your own MCP
Point Mockd at any custom MCP server. We render its tool descriptions, capture every call, and let you tune prompts against your own tools.
Why mock the server instead of wiring up the real one
Testing against live services means accounts, keys, quotas and the risk of changing real records. Mocking removes all of it — and gives you observability for free.
What you'd otherwise reach for — and where it stops short
An honest look: every tool below does something well. None of them give you a faithful MCP mock and a shareable trace in one place.
When to reach for something else
MCP Inspector
- Great for poking at a server you already run
- No synthetic data, no error injection, no saved trace
LangSmith / Langfuse
- Best-in-class tracing for production
- Instruments real runs — can't stand in for a backend
WireMock / Mockoon / Prism
- Solid general HTTP mocks
- Doesn't speak MCP — you author every response
Rolling your own
- Total control, zero licence cost
- You maintain a fake server + logs instead of shipping
Mock it before you wire it up
Test the integration with zero risk, then connect the real thing with confidence.