diff --git a/packages/agents-a365-observability/src/tracing/constants.ts b/packages/agents-a365-observability/src/tracing/constants.ts
index 162c91a2..c1539d8b 100644
--- a/packages/agents-a365-observability/src/tracing/constants.ts
+++ b/packages/agents-a365-observability/src/tracing/constants.ts
@@ -83,6 +83,7 @@ export class OpenTelemetryConstants {
   public static readonly AGENT_ID_KEY = 'gen_ai.agent.id';
   public static readonly GEN_AI_TASK_ID_KEY = 'gen_ai.task.id';
   public static readonly SESSION_ID_KEY = 'session.id';
+  public static readonly SESSION_DESCRIPTION_KEY = 'session.description';
   public static readonly GEN_AI_ICON_URI_KEY = 'gen_ai.agent365.icon_uri';
   public static readonly TENANT_ID_KEY = 'tenant.id';
 
diff --git a/packages/agents-a365-observability/src/tracing/middleware/BaggageBuilder.ts b/packages/agents-a365-observability/src/tracing/middleware/BaggageBuilder.ts
index d7feb434..f0640fd4 100644
--- a/packages/agents-a365-observability/src/tracing/middleware/BaggageBuilder.ts
+++ b/packages/agents-a365-observability/src/tracing/middleware/BaggageBuilder.ts
@@ -149,6 +149,16 @@ export class BaggageBuilder {
     return this;
   }
 
+  /**
+   * Set the session description baggage value.
+   * @param value The session description
+   * @returns Self for method chaining
+   */
+  sessionDescription(value: string | null | undefined): BaggageBuilder {
+    this.set(OpenTelemetryConstants.SESSION_DESCRIPTION_KEY, value);
+    return this;
+  }
+
   /**
    * Set the caller name baggage value.
    * @param value The caller name
diff --git a/packages/agents-a365-observability/src/tracing/processors/util.ts b/packages/agents-a365-observability/src/tracing/processors/util.ts
index 4b960dae..3738842c 100644
--- a/packages/agents-a365-observability/src/tracing/processors/util.ts
+++ b/packages/agents-a365-observability/src/tracing/processors/util.ts
@@ -19,6 +19,7 @@ export const GENERIC_ATTRIBUTES: readonly string[] = [
   consts.GEN_AI_AGENT_ID_KEY,
   consts.GEN_AI_AGENT_NAME_KEY,
   consts.GEN_AI_AGENT_DESCRIPTION_KEY,
+  consts.SESSION_DESCRIPTION_KEY,
   consts.GEN_AI_AGENT_USER_ID_KEY,
   consts.GEN_AI_AGENT_UPN_KEY,
   consts.GEN_AI_AGENT_BLUEPRINT_ID_KEY,
diff --git a/tests-agent/basic-agent-sdk-sample/src/agent.ts b/tests-agent/basic-agent-sdk-sample/src/agent.ts
index 75df9d42..c4ac4c16 100644
--- a/tests-agent/basic-agent-sdk-sample/src/agent.ts
+++ b/tests-agent/basic-agent-sdk-sample/src/agent.ts
@@ -61,6 +61,7 @@ agentApplication.onActivity(
       .agentId(agentInfo.agentId)
       .correlationId("7ff6dca0-917c-4bb0-b31a-794e533d8aad")
       .agentName(agentInfo.agentName)
+      .sessionDescription('Initial onboarding session')
       .conversationId(context.activity.conversation?.id)
       .callerId(context.activity.from?.aadObjectId)
       .callerUpn(context.activity.from?.id)
diff --git a/tests/observability/core/BaggageBuilder.test.ts b/tests/observability/core/BaggageBuilder.test.ts
index e3afd04a..43f255c5 100644
--- a/tests/observability/core/BaggageBuilder.test.ts
+++ b/tests/observability/core/BaggageBuilder.test.ts
@@ -140,9 +140,11 @@ describe('BaggageBuilder', () => {
         .agentId('agent-456')
         .correlationId('corr-789')
         .sessionId('session-0001')
+        .sessionDescription('My session desc')
         .build();
       const bag = propagation.getBaggage((scope as any).contextWithBaggage);
       expect(bag?.getEntry(OpenTelemetryConstants.SESSION_ID_KEY)?.value).toBe('session-0001');
+      expect(bag?.getEntry(OpenTelemetryConstants.SESSION_DESCRIPTION_KEY)?.value).toBe('My session desc');
     });
 
     it('should omit empty sessionId value', () => {
@@ -152,8 +154,15 @@ describe('BaggageBuilder', () => {
       const bag = propagation.getBaggage((scope as any).contextWithBaggage);
       expect(bag?.getEntry(OpenTelemetryConstants.SESSION_ID_KEY)).toBeUndefined();
     });
-  });
 
+    it('should omit null sessionDescription value', () => {
+      const scope = new BaggageBuilder()
+        .sessionDescription(null)
+        .build();
+      const bag = propagation.getBaggage((scope as any).contextWithBaggage);
+      expect(bag?.getEntry(OpenTelemetryConstants.SESSION_DESCRIPTION_KEY)).toBeUndefined();
+    });
+  });
 });
 
 describe('BaggageScope', () => {
diff --git a/tests/observability/core/SpanProcessor.test.ts b/tests/observability/core/SpanProcessor.test.ts
index 2b175904..784694be 100644
--- a/tests/observability/core/SpanProcessor.test.ts
+++ b/tests/observability/core/SpanProcessor.test.ts
@@ -68,6 +68,19 @@ describe('SpanProcessor', () => {
       expect(attrs[OpenTelemetryConstants.SESSION_ID_KEY]).toBe('session-abc');
     });
 
+    it('should copy sessionDescription from baggage to span', () => {
+      let baggage = propagation.createBaggage();
+      baggage = baggage.setEntry(OpenTelemetryConstants.SESSION_DESCRIPTION_KEY, { value: 'Test session description' });
+
+      const ctx = propagation.setBaggage(context.active(), baggage);
+      const tracer = provider.getTracer('test');
+      const testSpan = tracer.startSpan('test-span', { kind: SpanKind.CLIENT }, ctx as any);
+      testSpan.end();
+
+      const attrs = (testSpan as any)._attributes ?? (testSpan as any).attributes ?? {};
+      expect(attrs[OpenTelemetryConstants.SESSION_DESCRIPTION_KEY]).toBe('Test session description');
+    });
+
     it('should copy invoke agent attributes for invoke_agent operations', () => {
       // Set baggage with invoke agent specific fields
       const baggageEntries = {