diff --git a/dotnet/samples/02-agents/AgentOpenTelemetry/Program.cs b/dotnet/samples/02-agents/AgentOpenTelemetry/Program.cs
index d83a0cb3f54..6dded58e2cf 100644
--- a/dotnet/samples/02-agents/AgentOpenTelemetry/Program.cs
+++ b/dotnet/samples/02-agents/AgentOpenTelemetry/Program.cs
@@ -28,18 +28,18 @@
 var applicationInsightsConnectionString = Environment.GetEnvironmentVariable("APPLICATIONINSIGHTS_CONNECTION_STRING");
 
 // Create a resource to identify this service
-var resource = ResourceBuilder.CreateDefault()
+var resourceBuilder = ResourceBuilder.CreateDefault()
     .AddService(ServiceName, serviceVersion: "1.0.0")
     .AddAttributes(new Dictionary<string, object>
     {
         ["service.instance.id"] = Environment.MachineName,
-        ["deployment.environment"] = "development"
-    })
-    .Build();
+        ["deployment.environment"] = "development",
+        ["microsoft.foundry"] = "True"
+    });
 
 // Setup tracing with resource
 var tracerProviderBuilder = Sdk.CreateTracerProviderBuilder()
-    .SetResourceBuilder(ResourceBuilder.CreateDefault().AddService(ServiceName, serviceVersion: "1.0.0"))
+    .SetResourceBuilder(resourceBuilder)
     .AddSource(SourceName) // Our custom activity source
     .AddHttpClientInstrumentation() // Capture HTTP calls to OpenAI
     .AddOtlpExporter(options => options.Endpoint = new Uri(otlpEndpoint));
@@ -53,7 +53,7 @@
 
 // Setup metrics with resource and instrument name filtering
 using var meterProvider = Sdk.CreateMeterProviderBuilder()
-    .SetResourceBuilder(ResourceBuilder.CreateDefault().AddService(ServiceName, serviceVersion: "1.0.0"))
+    .SetResourceBuilder(resourceBuilder)
     .AddMeter(SourceName) // Our custom meter source
     .AddHttpClientInstrumentation() // HTTP client metrics
     .AddRuntimeInstrumentation() // .NET runtime metrics
@@ -66,7 +66,7 @@
     .SetMinimumLevel(LogLevel.Debug)
     .AddOpenTelemetry(options =>
     {
-        options.SetResourceBuilder(ResourceBuilder.CreateDefault().AddService(ServiceName, serviceVersion: "1.0.0"));
+        options.SetResourceBuilder(resourceBuilder);
         options.AddOtlpExporter(otlpOptions => otlpOptions.Endpoint = new Uri(otlpEndpoint));
         if (!string.IsNullOrWhiteSpace(applicationInsightsConnectionString))
         {
diff --git a/dotnet/samples/02-agents/AgentOpenTelemetry/README.md b/dotnet/samples/02-agents/AgentOpenTelemetry/README.md
index b4852fd9fcb..085d30f1b2f 100644
--- a/dotnet/samples/02-agents/AgentOpenTelemetry/README.md
+++ b/dotnet/samples/02-agents/AgentOpenTelemetry/README.md
@@ -30,6 +30,17 @@ graph TD
 
 ## Configuration
 
+### Shared telemetry resource
+
+Logs, traces, and metrics use a shared resource containing
+`"microsoft.foundry": "True"` (a string). The attribute also applies to HTTP and
+runtime instrumentation using these providers; it is not a per-span tag or metric
+dimension. Agent Framework does not configure resources for consuming .NET
+applications, so applications managing their own providers should add this
+attribute to their shared `ResourceBuilder`, or set
+`OTEL_RESOURCE_ATTRIBUTES=microsoft.foundry=True` before provider initialization
+(preserving any other configured resource attributes).
+
 ### Microsoft Foundry Setup
 Set the following environment variables:
 ```powershell
diff --git a/dotnet/samples/02-agents/AgentProviders/foundry/Agent_Step07_Observability/Program.cs b/dotnet/samples/02-agents/AgentProviders/foundry/Agent_Step07_Observability/Program.cs
index c1066fb0a01..12cbaaf7009 100644
--- a/dotnet/samples/02-agents/AgentProviders/foundry/Agent_Step07_Observability/Program.cs
+++ b/dotnet/samples/02-agents/AgentProviders/foundry/Agent_Step07_Observability/Program.cs
@@ -7,6 +7,7 @@
 using Azure.Monitor.OpenTelemetry.Exporter;
 using Microsoft.Agents.AI;
 using OpenTelemetry;
+using OpenTelemetry.Resources;
 using OpenTelemetry.Trace;
 
 string? applicationInsightsConnectionString = Environment.GetEnvironmentVariable("APPLICATIONINSIGHTS_CONNECTION_STRING");
@@ -16,6 +17,7 @@
 // Create TracerProvider with console exporter.
 string sourceName = Guid.NewGuid().ToString("N");
 TracerProviderBuilder tracerProviderBuilder = Sdk.CreateTracerProviderBuilder()
+    .ConfigureResource(resource => resource.AddAttributes([new("microsoft.foundry", "True")]))
     .AddSource(sourceName)
     .AddConsoleExporter();
 if (!string.IsNullOrWhiteSpace(applicationInsightsConnectionString))
diff --git a/dotnet/samples/02-agents/Agents/Agent_Step05_Observability/Program.cs b/dotnet/samples/02-agents/Agents/Agent_Step05_Observability/Program.cs
index 383038191ad..54c01f75007 100644
--- a/dotnet/samples/02-agents/Agents/Agent_Step05_Observability/Program.cs
+++ b/dotnet/samples/02-agents/Agents/Agent_Step05_Observability/Program.cs
@@ -10,6 +10,7 @@
 using Azure.Monitor.OpenTelemetry.Exporter;
 using Microsoft.Agents.AI;
 using OpenTelemetry;
+using OpenTelemetry.Resources;
 using OpenTelemetry.Trace;
 
 var endpoint = Environment.GetEnvironmentVariable("FOUNDRY_PROJECT_ENDPOINT") ?? throw new InvalidOperationException("FOUNDRY_PROJECT_ENDPOINT is not set.");
@@ -20,6 +21,7 @@
 // This will output the telemetry data to the console.
 string sourceName = Guid.NewGuid().ToString("N");
 var tracerProviderBuilder = Sdk.CreateTracerProviderBuilder()
+    .ConfigureResource(resource => resource.AddAttributes([new("microsoft.foundry", "True")]))
     .AddSource(sourceName)
     .AddConsoleExporter();
 if (!string.IsNullOrWhiteSpace(applicationInsightsConnectionString))
diff --git a/dotnet/samples/02-agents/Harness/BuildYourOwnClaw/Claw_Step04_ProductionReady/ClawAgent.Console/Program.cs b/dotnet/samples/02-agents/Harness/BuildYourOwnClaw/Claw_Step04_ProductionReady/ClawAgent.Console/Program.cs
index 4c0d4e346b9..dd5a0037754 100644
--- a/dotnet/samples/02-agents/Harness/BuildYourOwnClaw/Claw_Step04_ProductionReady/ClawAgent.Console/Program.cs
+++ b/dotnet/samples/02-agents/Harness/BuildYourOwnClaw/Claw_Step04_ProductionReady/ClawAgent.Console/Program.cs
@@ -17,7 +17,9 @@
 // Export telemetry only when an OTLP endpoint is configured. We deliberately avoid the
 // console exporter: this is an interactive app whose UI is rendered by
 // HarnessConsole.RunAgentAsync, and streaming spans/metrics to stdout corrupts that UI.
-var resourceBuilder = ResourceBuilder.CreateDefault().AddService(ServiceName, serviceVersion: "1.0.0");
+var resourceBuilder = ResourceBuilder.CreateDefault()
+    .AddService(ServiceName, serviceVersion: "1.0.0")
+    .AddAttributes([new("microsoft.foundry", "True")]);
 using var tracerProvider = telemetryEnabled
     ? Sdk.CreateTracerProviderBuilder()
         .SetResourceBuilder(resourceBuilder)
diff --git a/dotnet/samples/02-agents/Harness/Harness_Shared_Console/FileSpanExporter.cs b/dotnet/samples/02-agents/Harness/Harness_Shared_Console/FileSpanExporter.cs
index 4d64be8eae9..f1de352f116 100644
--- a/dotnet/samples/02-agents/Harness/Harness_Shared_Console/FileSpanExporter.cs
+++ b/dotnet/samples/02-agents/Harness/Harness_Shared_Console/FileSpanExporter.cs
@@ -3,6 +3,7 @@
 using System.Diagnostics;
 using System.Globalization;
 using OpenTelemetry;
+using OpenTelemetry.Resources;
 
 namespace Harness.Shared.Console;
 
@@ -27,6 +28,11 @@ public override ExportResult Export(in Batch<Activity> batch)
         lock (this._lock)
         {
             using var writer = new StreamWriter(this._filePath, append: true);
+            foreach (var attribute in this.ParentProvider.GetResource().Attributes)
+            {
+                writer.WriteLine($"Resource: {attribute.Key}: {attribute.Value}");
+            }
+
             foreach (var activity in batch)
             {
                 WriteActivity(writer, activity);
diff --git a/dotnet/samples/02-agents/Harness/Harness_Shared_Console/HarnessTracing.cs b/dotnet/samples/02-agents/Harness/Harness_Shared_Console/HarnessTracing.cs
index e79f79e0dd4..a87f5aa02dd 100644
--- a/dotnet/samples/02-agents/Harness/Harness_Shared_Console/HarnessTracing.cs
+++ b/dotnet/samples/02-agents/Harness/Harness_Shared_Console/HarnessTracing.cs
@@ -3,6 +3,7 @@
 #pragma warning disable VSTHRD002 // Synchronous waits are required by OpenTelemetry enrichment callbacks.
 
 using OpenTelemetry;
+using OpenTelemetry.Resources;
 using OpenTelemetry.Trace;
 
 namespace Harness.Shared.Console;
@@ -24,6 +25,7 @@ public static class HarnessTracing
         var traceLogPath = Path.Combine(AppContext.BaseDirectory, $"traces_{DateTime.UtcNow:yyyyMMdd_HHmmss}_{Guid.NewGuid()}.log");
 
         return Sdk.CreateTracerProviderBuilder()
+            .ConfigureResource(resource => resource.AddAttributes([new("microsoft.foundry", "True")]))
             .AddSource(sourceName)
             .AddHttpClientInstrumentation((options) =>
             {
diff --git a/dotnet/samples/03-workflows/Observability/ApplicationInsights/Program.cs b/dotnet/samples/03-workflows/Observability/ApplicationInsights/Program.cs
index 3d8d61b8a4e..f1b4669c68f 100644
--- a/dotnet/samples/03-workflows/Observability/ApplicationInsights/Program.cs
+++ b/dotnet/samples/03-workflows/Observability/ApplicationInsights/Program.cs
@@ -31,7 +31,8 @@ private static async Task Main()
 
         var resourceBuilder = ResourceBuilder
             .CreateDefault()
-            .AddService("WorkflowSample");
+            .AddService("WorkflowSample")
+            .AddAttributes([new("microsoft.foundry", "True")]);
 
         using var traceProvider = Sdk.CreateTracerProviderBuilder()
             .SetResourceBuilder(resourceBuilder)
diff --git a/dotnet/samples/03-workflows/Observability/AspireDashboard/Program.cs b/dotnet/samples/03-workflows/Observability/AspireDashboard/Program.cs
index 9e5a396656f..c6b19d1a2d6 100644
--- a/dotnet/samples/03-workflows/Observability/AspireDashboard/Program.cs
+++ b/dotnet/samples/03-workflows/Observability/AspireDashboard/Program.cs
@@ -33,7 +33,8 @@ private static async Task Main()
 
         var resourceBuilder = ResourceBuilder
             .CreateDefault()
-            .AddService("WorkflowSample");
+            .AddService("WorkflowSample")
+            .AddAttributes([new("microsoft.foundry", "True")]);
 
         using var traceProvider = Sdk.CreateTracerProviderBuilder()
             .SetResourceBuilder(resourceBuilder)
diff --git a/dotnet/samples/03-workflows/Observability/WorkflowAsAnAgent/Program.cs b/dotnet/samples/03-workflows/Observability/WorkflowAsAnAgent/Program.cs
index b6b67c6cf34..6029148d63b 100644
--- a/dotnet/samples/03-workflows/Observability/WorkflowAsAnAgent/Program.cs
+++ b/dotnet/samples/03-workflows/Observability/WorkflowAsAnAgent/Program.cs
@@ -54,7 +54,8 @@ private static async Task Main()
 
         var resourceBuilder = ResourceBuilder
             .CreateDefault()
-            .AddService("WorkflowSample");
+            .AddService("WorkflowSample")
+            .AddAttributes([new("microsoft.foundry", "True")]);
 
         var traceProviderBuilder = Sdk.CreateTracerProviderBuilder()
             .SetResourceBuilder(resourceBuilder)
diff --git a/dotnet/samples/04-hosting/FoundryHostedAgents/responses/Hosted-Observability/Program.cs b/dotnet/samples/04-hosting/FoundryHostedAgents/responses/Hosted-Observability/Program.cs
index 7b4f0cb947d..8b472662879 100644
--- a/dotnet/samples/04-hosting/FoundryHostedAgents/responses/Hosted-Observability/Program.cs
+++ b/dotnet/samples/04-hosting/FoundryHostedAgents/responses/Hosted-Observability/Program.cs
@@ -14,6 +14,7 @@
 using Microsoft.Agents.AI;
 using Microsoft.Agents.AI.Foundry.Hosting;
 using Microsoft.Extensions.AI;
+using OpenTelemetry.Resources;
 
 // Load a local .env file when present (local development only). In Foundry the
 // platform injects the required environment variables at runtime.
@@ -70,6 +71,8 @@ string GetWeather(
 // Host the agent using the Responses protocol.
 var builder = WebApplication.CreateBuilder(args);
 builder.Services.AddFoundryResponses(agent);
+builder.Services.AddOpenTelemetry()
+    .ConfigureResource(resource => resource.AddAttributes([new("microsoft.foundry", "True")]));
 
 var app = builder.Build();
 app.MapFoundryResponses();
diff --git a/dotnet/samples/05-end-to-end/AgentWebChat/AgentWebChat.ServiceDefaults/ServiceDefaultsExtensions.cs b/dotnet/samples/05-end-to-end/AgentWebChat/AgentWebChat.ServiceDefaults/ServiceDefaultsExtensions.cs
index 00af0166c8f..f5764a6d140 100644
--- a/dotnet/samples/05-end-to-end/AgentWebChat/AgentWebChat.ServiceDefaults/ServiceDefaultsExtensions.cs
+++ b/dotnet/samples/05-end-to-end/AgentWebChat/AgentWebChat.ServiceDefaults/ServiceDefaultsExtensions.cs
@@ -7,6 +7,7 @@
 using Microsoft.Extensions.Logging;
 using OpenTelemetry;
 using OpenTelemetry.Metrics;
+using OpenTelemetry.Resources;
 using OpenTelemetry.Trace;
 
 namespace Microsoft.Extensions.Hosting;
@@ -52,6 +53,7 @@ public static TBuilder ConfigureOpenTelemetry<TBuilder>(this TBuilder builder) w
         });
 
         builder.Services.AddOpenTelemetry()
+            .ConfigureResource(resource => resource.AddAttributes([new("microsoft.foundry", "True")]))
             .WithMetrics(metrics =>
             {
                 metrics.AddAspNetCoreInstrumentation()
diff --git a/dotnet/samples/05-end-to-end/DevUIAspireIntegration/DevUIIntegration.ServiceDefaults/Extensions.cs b/dotnet/samples/05-end-to-end/DevUIAspireIntegration/DevUIIntegration.ServiceDefaults/Extensions.cs
index 504bc71621b..89239d81b2a 100644
--- a/dotnet/samples/05-end-to-end/DevUIAspireIntegration/DevUIIntegration.ServiceDefaults/Extensions.cs
+++ b/dotnet/samples/05-end-to-end/DevUIAspireIntegration/DevUIIntegration.ServiceDefaults/Extensions.cs
@@ -7,6 +7,7 @@
 using Microsoft.Extensions.Logging;
 using OpenTelemetry;
 using OpenTelemetry.Metrics;
+using OpenTelemetry.Resources;
 using OpenTelemetry.Trace;
 
 namespace Microsoft.Extensions.Hosting;
@@ -56,6 +57,7 @@ public static TBuilder ConfigureOpenTelemetry<TBuilder>(this TBuilder builder) w
         });
 
         builder.Services.AddOpenTelemetry()
+            .ConfigureResource(resource => resource.AddAttributes([new("microsoft.foundry", "True")]))
             .WithMetrics(metrics =>
             {
                 metrics.AddAspNetCoreInstrumentation()
diff --git a/python/packages/core/README.md b/python/packages/core/README.md
index da095301470..a758b7c89dc 100644
--- a/python/packages/core/README.md
+++ b/python/packages/core/README.md
@@ -69,6 +69,14 @@ carry a documented feature-usage token.
 - `AGENT_FRAMEWORK_USER_AGENT_DISABLED=true` disables the entire Agent Framework
   User-Agent contribution, including the feature token.
 
+OpenTelemetry providers configured through `configure_otel_providers()` share a
+resource containing `"microsoft.foundry": "True"` (a string) by default. This
+resource attribute applies to logs, traces, and metrics, including other
+instrumentation using those providers. Existing environment and explicit resource
+attribute overrides retain their precedence. If you configure providers yourself,
+use `agent_framework.observability.create_resource()` for each provider or add the
+attribute to your own shared resource.
+
 See the following [getting started samples](https://github.com/microsoft/agent-framework/tree/main/python/samples/01-get-started) for more information.
 
 ## 2. Create a Simple Agent
diff --git a/python/packages/core/agent_framework/observability.py b/python/packages/core/agent_framework/observability.py
index fe24a7d138d..3f36c2430fa 100644
--- a/python/packages/core/agent_framework/observability.py
+++ b/python/packages/core/agent_framework/observability.py
@@ -851,6 +851,8 @@ def create_resource(
 
     This function reads standard OpenTelemetry environment variables to configure
     the resource, which identifies your service in telemetry backends.
+    Resources include the string attribute `microsoft.foundry="True"` by default,
+    shared by logs, traces, and metrics configured with this resource.
 
     The following environment variables are read:
     - OTEL_SERVICE_NAME: The name of the service (defaults to "agent_framework")
@@ -925,7 +927,7 @@ def create_resource(
     # Apply OTEL_RESOURCE_ATTRIBUTES first, as a base — everything applied after this
     # (attributes/kwargs, then service_name/service_version) takes precedence over it, so an
     # explicit value is never silently replaced by the environment.
-    resource_attributes: dict[str, Any] = {}
+    resource_attributes: dict[str, Any] = {"microsoft.foundry": "True"}
     if resource_attrs_env := os.getenv("OTEL_RESOURCE_ATTRIBUTES"):
         resource_attributes.update(_parse_headers(resource_attrs_env))
 
@@ -1624,6 +1626,8 @@ def configure_otel_providers(
 
     This method creates the exporters and providers for the application based on
     the provided values and environment variables and enables instrumentation.
+    All three signal providers share a resource that includes the string attribute
+    `microsoft.foundry="True"` by default.
 
     Call this method once during application startup, before any telemetry is captured.
     DO NOT call this method multiple times, as it may lead to unexpected behavior.
diff --git a/python/packages/core/tests/core/test_observability.py b/python/packages/core/tests/core/test_observability.py
index 1403b374a98..a935fab2216 100644
--- a/python/packages/core/tests/core/test_observability.py
+++ b/python/packages/core/tests/core/test_observability.py
@@ -1478,6 +1478,33 @@ def test_get_exporters_from_env_env_only_headers_unaffected_by_origin_guard(monk
 # region Test create_resource
 
 
+def test_create_resource_includes_foundry_attribute(monkeypatch: pytest.MonkeyPatch) -> None:
+    """Resources include the Foundry marker as a string, not a boolean."""
+    from agent_framework.observability import create_resource
+
+    monkeypatch.delenv("OTEL_RESOURCE_ATTRIBUTES", raising=False)
+
+    resource = create_resource()
+
+    assert resource.attributes["microsoft.foundry"] == "True"
+
+
+def test_create_resource_foundry_attribute_preserves_override_precedence(monkeypatch: pytest.MonkeyPatch) -> None:
+    """The default marker follows existing environment and explicit attribute precedence."""
+    from agent_framework.observability import create_resource
+
+    monkeypatch.setenv("OTEL_RESOURCE_ATTRIBUTES", "microsoft.foundry=environment")
+
+    assert create_resource().attributes["microsoft.foundry"] == "environment"
+    assert create_resource(attributes={"microsoft.foundry": "explicit"}).attributes["microsoft.foundry"] == "explicit"
+    assert (
+        create_resource(attributes={"microsoft.foundry": "explicit"}, **{"microsoft.foundry": "keyword"}).attributes[
+            "microsoft.foundry"
+        ]
+        == "keyword"
+    )
+
+
 def test_create_resource_from_env(monkeypatch):
     """Test create_resource reads OTEL environment variables."""
     from agent_framework.observability import create_resource
@@ -4418,6 +4445,60 @@ class TestAgent(AgentTelemetryLayer, _TestAgent):  # type: ignore[misc]  # pyref
 # region Test _configure_providers
 
 
+def test_configure_providers_share_foundry_resource() -> None:
+    """Exported logs, spans, and metrics carry the same marked resource."""
+    from opentelemetry.sdk._logs.export import InMemoryLogRecordExporter
+    from opentelemetry.sdk.metrics.export import InMemoryMetricReader, MetricExporter
+
+    from agent_framework.observability import ObservabilitySettings
+
+    span_exporter = InMemorySpanExporter()
+    log_exporter = InMemoryLogRecordExporter()
+    metric_reader = InMemoryMetricReader()
+    metric_exporter = Mock(spec=MetricExporter)
+    settings = ObservabilitySettings(
+        service_name="foundry-test",
+        resource_attributes={"deployment.environment": "test"},
+    )
+
+    with (
+        patch("opentelemetry.trace.set_tracer_provider") as set_tracer,
+        patch("opentelemetry._logs.set_logger_provider") as set_logger,
+        patch("opentelemetry.metrics.set_meter_provider") as set_meter,
+        patch("opentelemetry.sdk.metrics.export.PeriodicExportingMetricReader", return_value=metric_reader),
+        patch("agent_framework.observability.logger.addHandler"),
+    ):
+        settings._configure_providers([span_exporter, log_exporter, metric_exporter])
+
+    tracer_provider = set_tracer.call_args.args[0]
+    logger_provider = set_logger.call_args.args[0]
+    meter_provider = set_meter.call_args.args[0]
+    try:
+        with tracer_provider.get_tracer("test").start_as_current_span("test"):
+            pass
+        logger_provider.get_logger("test").emit(body="test log")
+        meter_provider.get_meter("test").create_counter("test_counter").add(1)
+        tracer_provider.force_flush()
+        logger_provider.force_flush()
+
+        metrics_data = metric_reader.get_metrics_data()
+        assert metrics_data is not None
+        resources = [
+            span_exporter.get_finished_spans()[0].resource,
+            log_exporter.get_finished_logs()[0].resource,
+            metrics_data.resource_metrics[0].resource,
+        ]
+        for resource in resources:
+            assert resource is resources[0]
+            assert resource.attributes["microsoft.foundry"] == "True"
+            assert resource.attributes["service.name"] == "foundry-test"
+            assert resource.attributes["deployment.environment"] == "test"
+    finally:
+        tracer_provider.shutdown()
+        logger_provider.shutdown()
+        meter_provider.shutdown()
+
+
 def test_configure_providers_with_span_exporters(monkeypatch):
     """Test _configure_providers correctly handles span exporters."""
     from unittest.mock import Mock, patch