feat(mcp): support SSE transport alongside Streamable HTTP#11647
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The MCP HTTP client path now picks between `streamable_http` (current MCP spec) and `sse` (older MCP transport, still used by postgres-mcp and other servers). Selection rules: - Explicit `transport: sse|streamable_http` in server config wins. - Otherwise, URLs whose path ends with `/sse` default to SSE. - Everything else defaults to `streamable_http` (unchanged behavior). Unblocks hermes agents connecting to MCP servers that only expose an SSE endpoint (e.g. the trapezius / slate-vela db MCP), without forcing every remote server to migrate to Streamable HTTP. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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…usResearch#11647) Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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Summary
The MCP HTTP client currently hardcodes the
streamable_httptransport, which blocks connecting to MCP servers that only expose the older SSE transport (e.g.postgres-mcpand many other community servers that haven't migrated). This adds transport selection without changing default behavior:transport: sse/transport: streamable_httpin the server config takes precedence./sse, default to SSE.streamable_http(unchanged from today).This lets users connect to either transport without forcing every remote server to migrate to Streamable HTTP. No changes to stdio servers or to default behavior for existing Streamable HTTP configs.
Test plan
pytest tests/tools/test_mcp_tool.py -q(includes new SSE transport tests)postgres-mcp) and confirm tools are discoverable🤖 Generated with Claude Code