# MCP Emulator (service host)

Create an instance:
curl -s -X POST https://mcp.emulators.dev/_emulate/instances
# Hosted deployments create instances lazily when the returned URL is first used. The instance URL is a capability: anyone who has it can read and modify the instance, so save the returned URLs. Never store real secrets in an emulator.
# The server generates an unguessable name. An optional {"instance":"<prefix>"} body adds a readable prefix.

Then use the returned providerBaseUrl / controlBaseUrl. Example below uses a sample instance.
# MCP Emulator

Stateful GitHub-backed MCP emulator with streamable HTTP transport, OAuth discovery, Dynamic Client Registration, authorization-code OAuth, and enterprise-managed ID-JAG token exchange.

Provider base URL: https://mcp.your-instance.emulators.dev
Control base URL: https://mcp.your-instance.emulators.dev/_emulate

Supported surfaces:
- Streamable HTTP MCP endpoint: supported at /mcp
- MCP OAuth authorization server: supported

Control endpoints:
- https://mcp.your-instance.emulators.dev/_emulate/manifest
- https://mcp.your-instance.emulators.dev/_emulate/coverage
- https://mcp.your-instance.emulators.dev/_emulate/connections
- https://mcp.your-instance.emulators.dev/_emulate/state
- https://mcp.your-instance.emulators.dev/_emulate/ledger
- https://mcp.your-instance.emulators.dev/_emulate/faults
- POST https://mcp.your-instance.emulators.dev/_emulate/credentials
- POST https://mcp.your-instance.emulators.dev/_emulate/seed
- POST https://mcp.your-instance.emulators.dev/_emulate/reset

Fault injection:
Arm a one-shot provider failure with a glob pathPattern, then inspect /ledger for faulted: true.
curl -s -X POST https://mcp.your-instance.emulators.dev/_emulate/faults \
  -H "content-type: application/json" \
  -d '{"match":{"method":"GET","pathPattern":"/v1/*"},"response":{"status":503,"body":{"error":"temporary"}}}'

Connect:

## MCP endpoint
https://mcp.your-instance.emulators.dev/mcp

## Base URL (env)
MCP_BASE_URL=https://mcp.your-instance.emulators.dev

## Create a credential
curl -s -X POST https://mcp.your-instance.emulators.dev/_emulate/credentials \
  -H "content-type: application/json" \
  -d '{"type":"bearer-token"}'

## Inspect requests
curl -s https://mcp.your-instance.emulators.dev/_emulate/ledger