deecfc68fa
fix(mcp): make run_tool wait_for timeout configurable, raise floor to 180s
The hardcoded `timeout=30.0` on `asyncio.wait_for(session.call_tool(...))`
in both `MCPSseClient.run_tool` and `MCPStreamableHttpClient.run_tool` was
truncating in-flight tool calls whose servers needed longer than 30s to
respond — most visibly large MCP composers whose tool responses include
sizeable catalogs.
Failure mode:
LLM → AgentExecutor → run_tool (1 call from the LLM)
├── attempt 1: get_session (probe ..._1 fails → swap ..._2)
│ → call_tool → 30s wait_for fires, TimeoutError raised
│ (server is still working — response ignored on arrival)
└── attempt 2: get_session (probe ..._2 fails → swap ..._3)
→ call_tool → 30s wait_for fires again
→ util.py dedup ("Repeated TimeoutError, not retrying")
→ ValueError("Maximum retries exceeded ...")
← AgentExecutor surfaces error → flow fails
The retry loop's TimeoutError dedup correctly stops looping once it sees
the same error twice, but every call against a slow server hit the same
ceiling and never had a chance to succeed. The session swaps between
attempts also produced excess HTTP churn against the server.
Both `run_tool` methods now resolve the timeout from
`get_settings_service().settings.mcp_server_timeout` (already used for
connection setup at lines 1617 / 1887, env: `LANGFLOW_MCP_SERVER_TIMEOUT`)
with a `max(setting, 180.0)` floor so default deployments don't end up
*shorter* than the previous hardcoded 30s — the Pydantic default for
`mcp_server_timeout` is 20.
Touched:
src/lfx/src/lfx/base/mcp/util.py
- L1677, L1689 (stdio run_tool)
- L1960, L1972 (streamable HTTP run_tool)
Unchanged on purpose:
- L1217, L1381 session-creation `timeout=30.0` (separate concern).
- L1060 `_validate_session_connectivity` 3.0s probe (separate
concern; addressed in follow-up if probe thrash persists).
Tuning:
- LANGFLOW_MCP_SERVER_TIMEOUT now governs both connection setup and
tool-call wait_for. The 180s floor clamps low values; raise the env
var above 180 to take effect.
Repro / verification:
- Trace run that previously failed at 67.08s with "Maximum retries
exceeded with repeated TimeoutError errors" against
`mcp-guardium_get_service_info` (47KB response payload) now
completes on attempt 1.
Co-authored-by: MANSURA HABIBA <MANSURAH@ie.ibm.com>
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