feat(mcp): add Streamable HTTP client to extra/mcp#592
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Adds MCPClientStreamableHTTP + StreamableHTTPServerParams alongside the existing SSE and stdio MCP clients, for servers that speak the Streamable HTTP transport (--transport http). Credentials are set on the httpx client so they ride every request including initialize; the transport's own headers arg is deprecated.
arnaudde
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Jul 16, 2026
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Summary
Adds a Streamable HTTP MCP client to
mistralai.extra.mcp, alongside the existing SSE and stdio clients, for MCP servers that speak the Streamable HTTP transport (--transport http).StreamableHTTPServerParams(url, headers, timeout, sse_read_timeout)MCPClientStreamableHTTP(MCPClientBase)whose_get_transportwiresmcp.client.streamable_http.streamable_http_clientto anhttpx.AsyncClient.Why
extra/mcpshipssse.pyandstdio.pybut no Streamable HTTP client. Streamable HTTP is the transport used by self-hosted / remote MCP servers (e.g. the official Notion MCP with--transport http), and it's the only option for callers that can't spawn a stdio subprocess.Credentials (bearer token, per-request integration headers) are set as the httpx client's default headers, so they are sent on every request including the
initializecall. This is required because recentmcpreleases deprecate and ignore the transport's ownheaders=argument (headers must live on thehttpx.AsyncClient).Notes
src/mistralai/extra/*is excluded from codegen (.genignore), so this hand-written module is safe.sse.py's structure andMCPClientBasecontract; no OAuth flow (not applicable to the bearer/header model this targets).Context
Currently consumers (Mistral Workflows SDK plugins) carry a local subclass of
MCPClientBaseto get this transport; once this lands and is released they can import it here instead, symmetric with SSE/stdio.