Transports

MCP-TUI supports every transport in the MCP specification. Pick by where the server runs.

STDIO

Best for local processes and command-launched servers. Most reliable.

mcp-tui --cmd <executable> --args "arg1,arg2,..."

Commands are validated for safety before launch. Process lifecycle is managed cross-platform (Unix and Windows).

HTTP / Streamable HTTP

For servers exposed as REST-shaped endpoints. Works for both direct JSON responses and text/event-stream upgrade responses, per the 2025-06-18 spec.

mcp-tui --transport http --url https://example.com/mcp tool list
mcp-tui --transport streamable-http --url https://example.com/mcp tool list

SEP-2243 method headers

--mcp-method-headers adds two advisory HTTP headers to every JSON-RPC request — MCP-Method (the JSON-RPC method) and MCP-Name (the tool/prompt name, or resource URI for resources/read) — so load balancers, proxies, and observability tools can route MCP traffic without parsing the body. It is off by default and applies only to the HTTP transports (STDIO ignores it).

mcp-tui --mcp-method-headers --transport http --url https://example.com/mcp tool list

Custom and OAuth headers

Add arbitrary headers with the repeatable --header KEY=VALUE. For servers behind OAuth (401 + WWW-Authenticate), use the --oauth-* flags instead of hand-crafting an Authorization header — see OAuth.

SSE

Long-lived event stream pattern: GET establishes the stream, POST sends requests, responses arrive on the stream.

mcp-tui --transport sse --url http://localhost:5001/sse tool list

The SSE client uses a no-timeout HTTP connection so the hanging GET stays open for the session.

When servers misbehave

• Wrong endpoint format — SSE servers must emit the first event as event: endpoint carrying the session URL.
• Redirect loops — usually a server bug, not a client issue.
• Mid-stream disconnects — MCP-TUI surfaces the error and the partial debug log; Ctrl+D opens the debug pane.

Reliability ranking

1. STDIO — local, deterministic, easy to debug.
2. HTTP / Streamable HTTP — request/response, simple to reason about.
3. SSE — works when the server matches the spec; quirky servers fail loudly.