diff --git a/apps/api/src/services/signal_observation_service.py b/apps/api/src/services/signal_observation_service.py
index 6f620b90..98e3cd8a 100644
--- a/apps/api/src/services/signal_observation_service.py
+++ b/apps/api/src/services/signal_observation_service.py
@@ -448,6 +448,7 @@ async def _add_observation_timeline(
 async def _run_pre_decision_investigation(incident: "Incident") -> int | None:
     started = time.monotonic()
     try:
+        await _ensure_signal_observation_mcp_runtime()
         from src.services.pre_decision_investigator import get_pre_decision_investigator
 
         await asyncio.wait_for(
@@ -471,6 +472,33 @@ async def _run_pre_decision_investigation(incident: "Incident") -> int | None:
         return int((time.monotonic() - started) * 1000)
 
 
+async def _ensure_signal_observation_mcp_runtime() -> None:
+    """Make one-off signal observation runs use the same MCP runtime as API startup."""
+    try:
+        from src.plugins.mcp.providers import register_all_providers
+        from src.plugins.mcp.registry import get_provider_registry
+        from src.services.mcp_tool_registry import get_mcp_tool_registry, init_mcp_tool_registry
+
+        provider_registry = get_provider_registry()
+        if len(provider_registry) == 0:
+            register_all_providers()
+            logger.info("signal_observation_mcp_providers_registered")
+
+        tool_registry = get_mcp_tool_registry()
+        if tool_registry.tool_count == 0:
+            await init_mcp_tool_registry()
+            logger.info(
+                "signal_observation_mcp_tool_registry_initialized",
+                providers=tool_registry.provider_count,
+                tools=tool_registry.tool_count,
+            )
+    except Exception as exc:
+        logger.warning(
+            "signal_observation_mcp_runtime_init_failed",
+            error=str(exc),
+        )
+
+
 async def record_signal_worker_observation(
     incident: "Incident",
     signal_data: dict[str, Any],
diff --git a/apps/api/src/workers/signal_worker.py b/apps/api/src/workers/signal_worker.py
index ed846e50..afb96f45 100644
--- a/apps/api/src/workers/signal_worker.py
+++ b/apps/api/src/workers/signal_worker.py
@@ -592,6 +592,16 @@ async def _main() -> None:
             message="Episodic Memory (DB) will be unavailable - incidents won't persist",
         )
 
+    try:
+        from src.plugins.mcp.providers import register_all_providers
+        from src.services.mcp_tool_registry import init_mcp_tool_registry
+
+        register_all_providers()
+        await init_mcp_tool_registry()
+        logger.info("signal_worker_mcp_runtime_initialized")
+    except Exception as e:
+        logger.warning("signal_worker_mcp_runtime_init_failed", error=str(e))
+
     # Write health files for K8s probes
     await _write_health_files()
 
diff --git a/apps/api/tests/test_mcp_tool_registry.py b/apps/api/tests/test_mcp_tool_registry.py
index 5510921d..5af5d367 100644
--- a/apps/api/tests/test_mcp_tool_registry.py
+++ b/apps/api/tests/test_mcp_tool_registry.py
@@ -337,6 +337,36 @@ class TestSuggestTools:
         registry = MCPToolRegistry()
         assert registry.suggest_tools() == []
 
+    @pytest.mark.asyncio
+    async def test_host_error_log_flood_gets_host_observability_tools(self):
+        registry = MCPToolRegistry()
+        ssh_provider = _StubProvider(
+            "ssh_host",
+            ["ssh_diagnose", "ssh_get_top_processes", "ssh_get_container_logs"],
+        )
+        signoz_provider = _StubProvider("signoz", ["query_logs"])
+        prometheus_provider = _StubProvider("prometheus", ["prometheus_query"])
+        await registry.register_provider(ssh_provider)
+        await registry.register_provider(signoz_provider)
+        await registry.register_provider(prometheus_provider)
+
+        tools = registry.suggest_tools(
+            alertname="HostErrorLogFlood",
+            incident_labels={
+                "target": "ollama",
+                "sensor_host": "ollama",
+                "sensor_ip": "192.168.0.188",
+                "host": "192.168.0.188",
+            },
+            max_tools=10,
+        )
+        names = [reg.tool.name for reg in tools]
+
+        assert "ssh_diagnose" in names
+        assert "ssh_get_top_processes" in names
+        assert "query_logs" in names
+        assert "prometheus_query" in names
+
     def test_get_all_tools_returns_all(self):
         registry = MCPToolRegistry()
         provider = _StubProvider("test", [])