diff --git a/firebase-ai/CHANGELOG.md b/firebase-ai/CHANGELOG.md
index 988d8d96b4a..eda86c88799 100644
--- a/firebase-ai/CHANGELOG.md
+++ b/firebase-ai/CHANGELOG.md
@@ -1,7 +1,8 @@
 # Unreleased
 
 - [changed] **Breaking Change**: Removed the `candidateCount` option from `LiveGenerationConfig`
-- [changed] Added support for the URL context tool, which allows the model to access content from provided public web URLs to inform and enhance its responses.
+- [changed] Added support for the URL context tool, which allows the model to access content from
+  provided public web URLs to inform and enhance its responses.
 
 # 17.3.0
 
diff --git a/firebase-ai/src/main/kotlin/com/google/firebase/ai/type/Candidate.kt b/firebase-ai/src/main/kotlin/com/google/firebase/ai/type/Candidate.kt
index 47038321793..bcadf6f292f 100644
--- a/firebase-ai/src/main/kotlin/com/google/firebase/ai/type/Candidate.kt
+++ b/firebase-ai/src/main/kotlin/com/google/firebase/ai/type/Candidate.kt
@@ -38,15 +38,17 @@ import kotlinx.serialization.json.JsonNames
  * enabled.
  */
 public class Candidate
+@OptIn(PublicPreviewAPI::class)
 internal constructor(
   public val content: Content,
   public val safetyRatings: List<SafetyRating>,
   public val citationMetadata: CitationMetadata?,
   public val finishReason: FinishReason?,
   public val groundingMetadata: GroundingMetadata?,
-  public val urlContextMetadata: UrlContextMetadata?
+  @property:PublicPreviewAPI public val urlContextMetadata: UrlContextMetadata?
 ) {
 
+  @OptIn(PublicPreviewAPI::class)
   @Serializable
   internal data class Internal(
     val content: Content.Internal? = null,
@@ -56,6 +58,8 @@ internal constructor(
     val groundingMetadata: GroundingMetadata.Internal? = null,
     val urlContextMetadata: UrlContextMetadata.Internal? = null
   ) {
+
+    @OptIn(PublicPreviewAPI::class)
     internal fun toPublic(): Candidate {
       val safetyRatings = safetyRatings?.mapNotNull { it.toPublic() }.orEmpty()
       val citations = citationMetadata?.toPublic()
@@ -505,7 +509,9 @@ public class Segment(
  */
 @PublicPreviewAPI
 public class UrlContextMetadata internal constructor(public val urlMetadata: List<UrlMetadata>) {
+
   @Serializable
+  @PublicPreviewAPI
   internal data class Internal(val urlMetadata: List<UrlMetadata.Internal>?) {
     internal fun toPublic() = UrlContextMetadata(urlMetadata?.map { it.toPublic() } ?: emptyList())
   }
diff --git a/firebase-ai/src/main/kotlin/com/google/firebase/ai/type/PublicPreviewAPI.kt b/firebase-ai/src/main/kotlin/com/google/firebase/ai/type/PublicPreviewAPI.kt
index bc4a53cc8eb..6ee2ea737dd 100644
--- a/firebase-ai/src/main/kotlin/com/google/firebase/ai/type/PublicPreviewAPI.kt
+++ b/firebase-ai/src/main/kotlin/com/google/firebase/ai/type/PublicPreviewAPI.kt
@@ -23,4 +23,9 @@ package com.google.firebase.ai.type
     "This API is part of an experimental public preview and may change in " +
       "backwards-incompatible ways without notice.",
 )
+@Target(
+  AnnotationTarget.CLASS,
+  AnnotationTarget.FUNCTION,
+  AnnotationTarget.PROPERTY
+)
 public annotation class PublicPreviewAPI()
diff --git a/firebase-ai/src/main/kotlin/com/google/firebase/ai/type/Tool.kt b/firebase-ai/src/main/kotlin/com/google/firebase/ai/type/Tool.kt
index 7dbf19cb48c..6c307cea0fe 100644
--- a/firebase-ai/src/main/kotlin/com/google/firebase/ai/type/Tool.kt
+++ b/firebase-ai/src/main/kotlin/com/google/firebase/ai/type/Tool.kt
@@ -24,12 +24,15 @@ import kotlinx.serialization.json.JsonObject
  * can be used to gather information or complete tasks.
  */
 public class Tool
+@OptIn(PublicPreviewAPI::class)
 internal constructor(
   internal val functionDeclarations: List<FunctionDeclaration>?,
   internal val googleSearch: GoogleSearch?,
   internal val codeExecution: JsonObject?,
-  internal val urlContext: UrlContext?,
+  @property:PublicPreviewAPI internal val urlContext: UrlContext?,
 ) {
+
+  @OptIn(PublicPreviewAPI::class)
   internal fun toInternal() =
     Internal(
       functionDeclarations?.map { it.toInternal() } ?: emptyList(),
@@ -37,6 +40,8 @@ internal constructor(
       codeExecution = this.codeExecution,
       urlContext = this.urlContext?.toInternal()
     )
+
+  @OptIn(PublicPreviewAPI::class)
   @Serializable
   internal data class Internal(
     val functionDeclarations: List<FunctionDeclaration.Internal>? = null,
@@ -47,6 +52,7 @@ internal constructor(
   )
   public companion object {
 
+    @OptIn(PublicPreviewAPI::class)
     private val codeExecutionInstance by lazy { Tool(null, null, JsonObject(emptyMap()), null) }
 
     /**
@@ -56,6 +62,7 @@ internal constructor(
      */
     @JvmStatic
     public fun functionDeclarations(functionDeclarations: List<FunctionDeclaration>): Tool {
+      @OptIn(PublicPreviewAPI::class)
       return Tool(functionDeclarations, null, null, null)
     }
 
@@ -97,6 +104,7 @@ internal constructor(
      */
     @JvmStatic
     public fun googleSearch(googleSearch: GoogleSearch = GoogleSearch()): Tool {
+      @OptIn(PublicPreviewAPI::class)
       return Tool(null, googleSearch, null, null)
     }
   }
diff --git a/firebase-ai/src/test/java/com/google/firebase/ai/DevAPIUnarySnapshotTests.kt b/firebase-ai/src/test/java/com/google/firebase/ai/DevAPIUnarySnapshotTests.kt
index 68e0b029ccc..e0ba386091b 100644
--- a/firebase-ai/src/test/java/com/google/firebase/ai/DevAPIUnarySnapshotTests.kt
+++ b/firebase-ai/src/test/java/com/google/firebase/ai/DevAPIUnarySnapshotTests.kt
@@ -18,6 +18,7 @@ package com.google.firebase.ai
 
 import com.google.firebase.ai.type.FinishReason
 import com.google.firebase.ai.type.InvalidAPIKeyException
+import com.google.firebase.ai.type.PublicPreviewAPI
 import com.google.firebase.ai.type.ResponseStoppedException
 import com.google.firebase.ai.type.ServerException
 import com.google.firebase.ai.type.UrlRetrievalStatus
@@ -135,6 +136,7 @@ internal class DevAPIUnarySnapshotTests {
       }
     }
 
+  @OptIn(PublicPreviewAPI::class)
   @Test
   fun `url context`() =
     goldenDevAPIUnaryFile("unary-success-url-context.json") {
@@ -167,6 +169,7 @@ internal class DevAPIUnarySnapshotTests {
       }
     }
 
+  @OptIn(PublicPreviewAPI::class)
   @Test
   fun `url context mixed validity`() =
     goldenDevAPIUnaryFile("unary-success-url-context-mixed-validity.json") {
diff --git a/firebase-ai/src/test/java/com/google/firebase/ai/GenerativeModelTesting.kt b/firebase-ai/src/test/java/com/google/firebase/ai/GenerativeModelTesting.kt
index 8301f48d968..1c6e087dd80 100644
--- a/firebase-ai/src/test/java/com/google/firebase/ai/GenerativeModelTesting.kt
+++ b/firebase-ai/src/test/java/com/google/firebase/ai/GenerativeModelTesting.kt
@@ -23,6 +23,7 @@ import com.google.firebase.ai.common.util.doBlocking
 import com.google.firebase.ai.type.Candidate
 import com.google.firebase.ai.type.Content
 import com.google.firebase.ai.type.GenerateContentResponse
+import com.google.firebase.ai.type.PublicPreviewAPI
 import com.google.firebase.ai.type.RequestOptions
 import com.google.firebase.ai.type.ServerException
 import com.google.firebase.ai.type.TextPart
@@ -41,7 +42,6 @@ import io.ktor.http.content.TextContent
 import io.ktor.http.headersOf
 import kotlin.time.Duration.Companion.seconds
 import kotlinx.coroutines.withTimeout
-import kotlinx.serialization.ExperimentalSerializationApi
 import kotlinx.serialization.encodeToString
 import org.junit.Before
 import org.junit.Test
@@ -146,7 +146,7 @@ internal class GenerativeModelTesting {
     exception.message shouldContain "location"
   }
 
-  @OptIn(ExperimentalSerializationApi::class)
+  @OptIn(PublicPreviewAPI::class)
   private fun generateContentResponseAsJsonString(text: String): String {
     return JSON.encodeToString(
       GenerateContentResponse.Internal(
diff --git a/firebase-ai/src/test/java/com/google/firebase/ai/common/APIControllerTests.kt b/firebase-ai/src/test/java/com/google/firebase/ai/common/APIControllerTests.kt
index aa47afae7da..8804e386d33 100644
--- a/firebase-ai/src/test/java/com/google/firebase/ai/common/APIControllerTests.kt
+++ b/firebase-ai/src/test/java/com/google/firebase/ai/common/APIControllerTests.kt
@@ -26,6 +26,7 @@ import com.google.firebase.ai.type.Content
 import com.google.firebase.ai.type.CountTokensResponse
 import com.google.firebase.ai.type.FunctionCallingConfig
 import com.google.firebase.ai.type.GoogleSearch
+import com.google.firebase.ai.type.PublicPreviewAPI
 import com.google.firebase.ai.type.RequestOptions
 import com.google.firebase.ai.type.TextPart
 import com.google.firebase.ai.type.Tool
@@ -285,6 +286,7 @@ internal class RequestFormatTests {
       )
 
     withTimeout(5.seconds) {
+      @OptIn(PublicPreviewAPI::class)
       controller
         .generateContentStream(
           GenerateContentRequest(
@@ -323,6 +325,7 @@ internal class RequestFormatTests {
       )
 
     withTimeout(5.seconds) {
+      @OptIn(PublicPreviewAPI::class)
       controller
         .generateContentStream(
           GenerateContentRequest(
@@ -432,6 +435,7 @@ internal class RequestFormatTests {
       )
 
     withTimeout(5.seconds) {
+      @OptIn(PublicPreviewAPI::class)
       controller
         .generateContentStream(
           GenerateContentRequest(
diff --git a/firebase-ai/src/test/java/com/google/firebase/ai/common/util/tests.kt b/firebase-ai/src/test/java/com/google/firebase/ai/common/util/tests.kt
index 6cc501cedd5..d9081cae371 100644
--- a/firebase-ai/src/test/java/com/google/firebase/ai/common/util/tests.kt
+++ b/firebase-ai/src/test/java/com/google/firebase/ai/common/util/tests.kt
@@ -24,6 +24,7 @@ import com.google.firebase.ai.common.JSON
 import com.google.firebase.ai.type.Candidate
 import com.google.firebase.ai.type.Content
 import com.google.firebase.ai.type.GenerateContentResponse
+import com.google.firebase.ai.type.PublicPreviewAPI
 import com.google.firebase.ai.type.RequestOptions
 import com.google.firebase.ai.type.TextPart
 import io.ktor.client.engine.mock.MockEngine
@@ -32,7 +33,6 @@ import io.ktor.http.HttpHeaders
 import io.ktor.http.HttpStatusCode
 import io.ktor.http.headersOf
 import io.ktor.utils.io.ByteChannel
-import kotlinx.serialization.ExperimentalSerializationApi
 import kotlinx.serialization.encodeToString
 import org.mockito.Mockito
 
@@ -44,7 +44,7 @@ internal fun prepareStreamingResponse(
   response: List<GenerateContentResponse.Internal>
 ): List<ByteArray> = response.map { "data: ${JSON.encodeToString(it)}$SSE_SEPARATOR".toByteArray() }
 
-@OptIn(ExperimentalSerializationApi::class)
+@OptIn(PublicPreviewAPI::class)
 internal fun createResponses(vararg text: String): List<GenerateContentResponse.Internal> {
   val candidates =
     text.map { Candidate.Internal(Content.Internal(parts = listOf(TextPart.Internal(it)))) }
diff --git a/firebase-ai/src/test/java/com/google/firebase/ai/type/ToolTest.kt b/firebase-ai/src/test/java/com/google/firebase/ai/type/ToolTest.kt
index bb967470d84..538792be5f7 100644
--- a/firebase-ai/src/test/java/com/google/firebase/ai/type/ToolTest.kt
+++ b/firebase-ai/src/test/java/com/google/firebase/ai/type/ToolTest.kt
@@ -28,6 +28,7 @@ internal class ToolTest {
     tool.googleSearch.shouldNotBeNull()
     tool.functionDeclarations.shouldBeNull()
     tool.codeExecution.shouldBeNull()
+    @OptIn(PublicPreviewAPI::class)
     tool.urlContext.shouldBeNull()
   }
 
@@ -39,6 +40,7 @@ internal class ToolTest {
     tool.functionDeclarations?.first() shouldBe functionDeclaration
     tool.googleSearch.shouldBeNull()
     tool.codeExecution.shouldBeNull()
+    @OptIn(PublicPreviewAPI::class)
     tool.urlContext.shouldBeNull()
   }
 
@@ -48,9 +50,11 @@ internal class ToolTest {
     tool.codeExecution.shouldNotBeNull()
     tool.functionDeclarations.shouldBeNull()
     tool.googleSearch.shouldBeNull()
+    @OptIn(PublicPreviewAPI::class)
     tool.urlContext.shouldBeNull()
   }
 
+  @OptIn(PublicPreviewAPI::class)
   @Test
   fun `urlContext() creates a tool with a urlContext property`() {
     val tool = Tool.urlContext()
@@ -58,6 +62,7 @@ internal class ToolTest {
     tool.googleSearch.shouldBeNull()
     tool.functionDeclarations.shouldBeNull()
     tool.codeExecution.shouldBeNull()
+    @OptIn(PublicPreviewAPI::class)
     tool.urlContext.shouldNotBeNull()
   }
 }