diff --git a/src/Observability/Runtime/DTOs/Builders/ExecuteToolDataBuilder.cs b/src/Observability/Runtime/DTOs/Builders/ExecuteToolDataBuilder.cs
index 3412870a..08169058 100644
--- a/src/Observability/Runtime/DTOs/Builders/ExecuteToolDataBuilder.cs
+++ b/src/Observability/Runtime/DTOs/Builders/ExecuteToolDataBuilder.cs
@@ -89,12 +89,13 @@ private static void AddToolDetails(
             Dictionary<string, object?> attributes,
             ToolCallDetails toolCallDetails)
         {
-            var (toolName, arguments, toolCallId, description, toolType, endpoint) = toolCallDetails;
+            var (toolName, arguments, toolCallId, description, toolType, endpoint, toolServerName) = toolCallDetails;
             AddIfNotNull(attributes, OpenTelemetryConstants.GenAiToolNameKey, toolName);
             AddIfNotNull(attributes, OpenTelemetryConstants.GenAiToolArgumentsKey, arguments);
             AddIfNotNull(attributes, OpenTelemetryConstants.GenAiToolCallIdKey, toolCallId);
             AddIfNotNull(attributes, OpenTelemetryConstants.GenAiToolDescriptionKey, description);
             AddIfNotNull(attributes, OpenTelemetryConstants.GenAiToolTypeKey, toolType);
+            AddIfNotNull(attributes, OpenTelemetryConstants.GenAiToolServerNameKey, toolServerName);
             if (endpoint != null)
             {
                 AddIfNotNull(attributes, OpenTelemetryConstants.ServerAddressKey, endpoint.Host);
diff --git a/src/Observability/Runtime/Tracing/Contracts/ToolCallDetails.cs b/src/Observability/Runtime/Tracing/Contracts/ToolCallDetails.cs
index 33805b39..095c5e82 100644
--- a/src/Observability/Runtime/Tracing/Contracts/ToolCallDetails.cs
+++ b/src/Observability/Runtime/Tracing/Contracts/ToolCallDetails.cs
@@ -20,13 +20,15 @@ public sealed class ToolCallDetails : IEquatable<ToolCallDetails>
         /// <param name="description">Optional description of the tool call.</param>
         /// <param name="toolType">Optional type classification for the tool.</param>
         /// <param name="endpoint">Optional endpoint for remote tool execution.</param>
+        /// <param name="toolServerName">Optional server name for the tool.</param>
         public ToolCallDetails(
             string toolName,
             string? arguments,
             string? toolCallId = null,
             string? description = null,
             string? toolType = null,
-            Uri? endpoint = null)
+            Uri? endpoint = null,
+            string? toolServerName = null)
         {
             ToolName = toolName;
             Arguments = arguments;
@@ -34,6 +36,7 @@ public ToolCallDetails(
             Description = description;
             ToolType = toolType;
             Endpoint = endpoint;
+            ToolServerName = toolServerName;
         }
 
         /// <summary>
@@ -66,6 +69,11 @@ public ToolCallDetails(
         /// </summary>
         public Uri? Endpoint { get; }
 
+        /// <summary>
+        /// Gets the server name associated with the tool, when provided.
+        /// </summary>
+        public string? ToolServerName { get; }
+
         /// <summary>
         /// Deconstructs this instance into individual tool call components.
         /// </summary>
@@ -75,7 +83,8 @@ public ToolCallDetails(
         /// <param name="description">Receives the human-readable description.</param>
         /// <param name="toolType">Receives the type hint.</param>
         /// <param name="endpoint">Receives the endpoint.</param>
-        public void Deconstruct(out string toolName, out string? arguments, out string? toolCallId, out string? description, out string? toolType, out Uri? endpoint)
+        /// <param name="toolServerName">Receives the tool server name.</param>
+        public void Deconstruct(out string toolName, out string? arguments, out string? toolCallId, out string? description, out string? toolType, out Uri? endpoint, out string? toolServerName)
         {
             toolName = ToolName;
             arguments = Arguments;
@@ -83,6 +92,7 @@ public void Deconstruct(out string toolName, out string? arguments, out string?
             description = Description;
             toolType = ToolType;
             endpoint = Endpoint;
+            toolServerName = ToolServerName;
         }
 
         /// <inheritdoc/>
@@ -98,7 +108,8 @@ public bool Equals(ToolCallDetails? other)
                    string.Equals(ToolCallId, other.ToolCallId, StringComparison.Ordinal) &&
                    string.Equals(Description, other.Description, StringComparison.Ordinal) &&
                    string.Equals(ToolType, other.ToolType, StringComparison.Ordinal) &&
-                   EqualityComparer<Uri?>.Default.Equals(Endpoint, other.Endpoint);
+                   EqualityComparer<Uri?>.Default.Equals(Endpoint, other.Endpoint) &&
+                   string.Equals(ToolServerName, other.ToolServerName, StringComparison.Ordinal);
         }
 
         /// <inheritdoc/>
@@ -119,6 +130,7 @@ public override int GetHashCode()
                 hash = (hash * 31) + (Description != null ? StringComparer.Ordinal.GetHashCode(Description) : 0);
                 hash = (hash * 31) + (ToolType != null ? StringComparer.Ordinal.GetHashCode(ToolType) : 0);
                 hash = (hash * 31) + EqualityComparer<Uri?>.Default.GetHashCode(Endpoint);
+                hash = (hash * 31) + (ToolServerName != null ? StringComparer.Ordinal.GetHashCode(ToolServerName) : 0);
                 return hash;
             }
         }
diff --git a/src/Observability/Runtime/Tracing/Scopes/ExecuteToolScope.cs b/src/Observability/Runtime/Tracing/Scopes/ExecuteToolScope.cs
index 115b517e..cb6dde68 100644
--- a/src/Observability/Runtime/Tracing/Scopes/ExecuteToolScope.cs
+++ b/src/Observability/Runtime/Tracing/Scopes/ExecuteToolScope.cs
@@ -56,12 +56,13 @@ private ExecuteToolScope(ToolCallDetails details, AgentDetails agentDetails, Ten
                 conversationId: conversationId,
                 sourceMetadata: sourceMetadata)
         {
-            var (toolName, arguments, toolCallId, description, toolType, endpoint) = details;
+            var (toolName, arguments, toolCallId, description, toolType, endpoint, toolServerName) = details;
             SetTagMaybe(OpenTelemetryConstants.GenAiToolNameKey, toolName);
             SetTagMaybe(OpenTelemetryConstants.GenAiToolArgumentsKey, arguments);
             SetTagMaybe(OpenTelemetryConstants.GenAiToolTypeKey, toolType);
             SetTagMaybe(OpenTelemetryConstants.GenAiToolCallIdKey, toolCallId);
             SetTagMaybe(OpenTelemetryConstants.GenAiToolDescriptionKey, description);
+            SetTagMaybe(OpenTelemetryConstants.GenAiToolServerNameKey, toolServerName);
             SetTagMaybe(OpenTelemetryConstants.ThreatDiagnosticsSummaryKey, threatDiagnosticsSummary?.ToJson());
 
             if (endpoint !=null)
diff --git a/src/Observability/Runtime/Tracing/Scopes/OpenTelemetryConstants.cs b/src/Observability/Runtime/Tracing/Scopes/OpenTelemetryConstants.cs
index 473e3354..7388bb66 100644
--- a/src/Observability/Runtime/Tracing/Scopes/OpenTelemetryConstants.cs
+++ b/src/Observability/Runtime/Tracing/Scopes/OpenTelemetryConstants.cs
@@ -134,6 +134,11 @@ public enum OperationNames
         /// The GenAI tool type key.
         /// </summary>
         public const string GenAiToolTypeKey = "gen_ai.tool.type";
+
+        /// <summary>
+        /// The GenAI tool server name key.
+        /// </summary>
+        public const string GenAiToolServerNameKey = "gen_ai.tool.server.name";
         #endregion
 
         /// <summary>
diff --git a/src/Tests/Microsoft.Agents.A365.Observability.Runtime.IntegrationTests/Agent365ExporterE2ETests.cs b/src/Tests/Microsoft.Agents.A365.Observability.Runtime.IntegrationTests/Agent365ExporterE2ETests.cs
index f6d055b9..b23e7fd5 100644
--- a/src/Tests/Microsoft.Agents.A365.Observability.Runtime.IntegrationTests/Agent365ExporterE2ETests.cs
+++ b/src/Tests/Microsoft.Agents.A365.Observability.Runtime.IntegrationTests/Agent365ExporterE2ETests.cs
@@ -144,7 +144,8 @@ public async Task AddTracing_And_ExecuteToolScope_ExporterMakesExpectedRequest()
                 toolCallId: "call-456",
                 description: "Test tool call description",
                 toolType: "custom-type",
-                endpoint: endpoint);
+                endpoint: endpoint,
+                toolServerName: "test-tool-server");
 
             var expectedThreatDiagnosticsSummary = new ThreatDiagnosticsSummary(
                 blockAction: false,
@@ -190,6 +191,7 @@ public async Task AddTracing_And_ExecuteToolScope_ExporterMakesExpectedRequest()
             this.GetAttribute(attributes, "gen_ai.tool.call.id").Should().Be(toolCallDetails.ToolCallId);
             this.GetAttribute(attributes, "gen_ai.tool.description").Should().Be(toolCallDetails.Description);
             this.GetAttribute(attributes, "gen_ai.tool.type").Should().Be(toolCallDetails.ToolType);
+            this.GetAttribute(attributes, "gen_ai.tool.server.name").Should().Be(toolCallDetails.ToolServerName);
             this.GetAttribute(attributes, "server.address").Should().Be(endpoint.Host);
             this.GetAttribute(attributes, "server.port").Should().Be(endpoint.Port.ToString());
             this.GetAttribute(attributes, "gen_ai.event.content").Should().Be("Tool response content");
diff --git a/src/Tests/Microsoft.Agents.A365.Observability.Runtime.Tests/DTOs/Builders/ExecuteToolDataBuilderTests.cs b/src/Tests/Microsoft.Agents.A365.Observability.Runtime.Tests/DTOs/Builders/ExecuteToolDataBuilderTests.cs
index 81fd2f3d..5469eb8d 100644
--- a/src/Tests/Microsoft.Agents.A365.Observability.Runtime.Tests/DTOs/Builders/ExecuteToolDataBuilderTests.cs
+++ b/src/Tests/Microsoft.Agents.A365.Observability.Runtime.Tests/DTOs/Builders/ExecuteToolDataBuilderTests.cs
@@ -51,7 +51,7 @@ public void Build_WithFullToolDetails_IncludesAllToolAttributes()
         {
             // Arrange
             var endpoint = new Uri("https://example.com:7071");
-            var toolDetails = new ToolCallDetails("toolB", "{b:2}", "call-123", "Test tool", "function", endpoint);
+            var toolDetails = new ToolCallDetails("toolB", "{b:2}", "call-123", "Test tool", "function", endpoint, "my-tool-server");
             var agent = new AgentDetails("agent-2", "AgentTwo", "Desc", agentAUID: "auid", agentUPN: "upn@example.com", agentBlueprintId: "bp-1");
             var tenant = new TenantDetails(Guid.NewGuid());
             var conversationId = "conv-full";
@@ -64,6 +64,7 @@ public void Build_WithFullToolDetails_IncludesAllToolAttributes()
             attrs.Should().ContainKey(OpenTelemetryConstants.GenAiToolCallIdKey).WhoseValue.Should().Be("call-123");
             attrs.Should().ContainKey(OpenTelemetryConstants.GenAiToolDescriptionKey).WhoseValue.Should().Be("Test tool");
             attrs.Should().ContainKey(OpenTelemetryConstants.GenAiToolTypeKey).WhoseValue.Should().Be("function");
+            attrs.Should().ContainKey(OpenTelemetryConstants.GenAiToolServerNameKey).WhoseValue.Should().Be("my-tool-server");
             attrs.Should().ContainKey(OpenTelemetryConstants.ServerAddressKey).WhoseValue.Should().Be("example.com");
             attrs.Should().ContainKey(OpenTelemetryConstants.ServerPortKey).WhoseValue.Should().Be(7071);
             attrs.Should().ContainKey(OpenTelemetryConstants.GenAiAgentAUIDKey).WhoseValue.Should().Be("auid");
@@ -153,6 +154,7 @@ public void Build_WithNullOptionalParameters_OmitsThoseAttributes()
             data.Attributes.Should().NotContainKey(OpenTelemetryConstants.GenAiToolCallIdKey);
             data.Attributes.Should().NotContainKey(OpenTelemetryConstants.GenAiToolDescriptionKey);
             data.Attributes.Should().NotContainKey(OpenTelemetryConstants.GenAiToolTypeKey);
+            data.Attributes.Should().NotContainKey(OpenTelemetryConstants.GenAiToolServerNameKey);
             data.Attributes.Should().ContainKey(OpenTelemetryConstants.GenAiConversationIdKey).WhoseValue.Should().Be(conversationId);
             data.Attributes.Should().NotContainKey(OpenTelemetryConstants.GenAiEventContent);
         }
@@ -201,7 +203,7 @@ public void Build_WithAllParameters_SetsAllExpectedAttributes()
         {
             // Arrange
             var endpoint = new Uri("https://example.org:6060");
-            var toolDetails = new ToolCallDetails("toolJ", "{x:1}", "call-999", "Full tool", "extension", endpoint);
+            var toolDetails = new ToolCallDetails("toolJ", "{x:1}", "call-999", "Full tool", "extension", endpoint, "full-tool-server");
             var agent = new AgentDetails("agent-10", "AgentTen", "Desc", agentAUID: "auid10", agentUPN: "upn10@example.com", agentBlueprintId: "bp-10");
             var tenant = new TenantDetails(Guid.NewGuid());
             var conversationId = "conv-all";
@@ -228,6 +230,7 @@ public void Build_WithAllParameters_SetsAllExpectedAttributes()
             attrs.Should().ContainKey(OpenTelemetryConstants.GenAiToolCallIdKey);
             attrs.Should().ContainKey(OpenTelemetryConstants.GenAiToolDescriptionKey);
             attrs.Should().ContainKey(OpenTelemetryConstants.GenAiToolTypeKey);
+            attrs.Should().ContainKey(OpenTelemetryConstants.GenAiToolServerNameKey).WhoseValue.Should().Be("full-tool-server");
             attrs.Should().ContainKey(OpenTelemetryConstants.GenAiConversationIdKey);
             attrs.Should().ContainKey(OpenTelemetryConstants.GenAiEventContent);
             data.StartTime.Should().Be(start);
diff --git a/src/Tests/Microsoft.Agents.A365.Observability.Runtime.Tests/Tracing/Scopes/ExecuteToolScopeTest.cs b/src/Tests/Microsoft.Agents.A365.Observability.Runtime.Tests/Tracing/Scopes/ExecuteToolScopeTest.cs
index 06407830..46d106ef 100644
--- a/src/Tests/Microsoft.Agents.A365.Observability.Runtime.Tests/Tracing/Scopes/ExecuteToolScopeTest.cs
+++ b/src/Tests/Microsoft.Agents.A365.Observability.Runtime.Tests/Tracing/Scopes/ExecuteToolScopeTest.cs
@@ -207,4 +207,26 @@ public void RecordThreatDiagnosticsSummary_SetsTagCorrectly()
         tagValue.Should().Contain("\"reason\":\"Blocked due to policy violation.\"");
         tagValue.Should().Contain("data-loss-prevention");
     }
+
+    [TestMethod]
+    public void Start_ToolServerName_IsSetCorrectly()
+    {
+        // Arrange
+        const string expectedToolServerName = "test-tool-server";
+        var toolCallDetails = new ToolCallDetails(
+            toolName: "TestTool",
+            arguments: "args",
+            toolServerName: expectedToolServerName);
+        var agentDetails = Util.GetAgentDetails();
+        var tenantDetails = Util.GetTenantDetails();
+
+        // Act
+        var activity = ListenForActivity(() =>
+        {
+            using var scope = ExecuteToolScope.Start(toolCallDetails, agentDetails, tenantDetails);
+        });
+
+        // Assert
+        activity.ShouldHaveTag(OpenTelemetryConstants.GenAiToolServerNameKey, expectedToolServerName);
+    }
 }
\ No newline at end of file