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qai supports three MCP transport types for connecting to target servers. The transport determines how messages are exchanged between qai and the server under test.

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Transport Types

TransportFlag ValueConnectionUse Case
stdiostdioSpawns server as child process, communicates via stdin/stdoutLocal servers, npm packages, Python servers
SSEsseHTTP connection with Server-Sent EventsRemote servers using the legacy SSE transport
Streamable HTTPstreamable-httpBidirectional HTTP streamingRemote servers using the current MCP spec

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stdio

The most common transport. qai spawns the server as a child process and communicates over standard input/output. It is the default for web UI workflow launches, but CLI commands require an explicit --transport stdio flag. CLI usage: 
# Audit a local MCP server
qai audit scan --transport stdio --command "npx @modelcontextprotocol/server-memory"

# Proxy a local server
qai proxy start --transport stdio --target-command "python my_server.py"

# Inject with a local target
qai inject serve --transport stdio
The --command flag specifies the shell command to start the server. qai handles process lifecycle (spawn, communicate, terminate). When to use: Local development, testing npm or Python MCP servers, CI pipelines where the server runs on the same machine.

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SSE

Server-Sent Events over HTTP. Connect to a remote MCP server that implements the legacy SSE transport. CLI usage: 
qai audit scan --transport sse --url "https://mcp-server.example.com/sse"

qai proxy start --transport sse --target-url "https://mcp-server.example.com/sse"
The --url flag specifies the server’s SSE endpoint. When to use: Remote servers using the older MCP SSE protocol, servers behind firewalls that allow HTTP.

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Streamable HTTP

Bidirectional HTTP streaming. Connect to a remote MCP server implementing the current Streamable HTTP transport specification. CLI usage: 
qai audit scan --transport streamable-http --url "https://mcp-server.example.com/mcp"

qai proxy start --transport streamable-http --target-url "https://mcp-server.example.com/mcp"
When to use: Modern MCP servers, cloud deployments, servers requiring bidirectional communication.

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Default Transport

The default transport is stdio. You can set a different default in the web UI under Settings > Defaults > Audit Transport, which applies to workflow launches from the web UI. CLI commands always require an explicit --transport flag — there is no global CLI default.

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Module-Specific Notes

Audit: Uses --transport, --command (stdio), and --url (SSE/HTTP) flags on qai audit scan and qai audit enumerate. Proxy: Uses --transport, --target-command (stdio), and --target-url (SSE/HTTP) flags on qai proxy start and qai proxy replay. Inject: The inject server (qai inject serve) uses --transport to control how the malicious MCP server is exposed. Campaigns use the litellm backend (not MCP transport) to communicate with LLM providers. Chain: Transport for chain execution is configured in chain-targets.yaml (per-target transport and connection details).