feat: enable server side MCP and disable all other AFC when server side MCP is configured.

src/main/java/com/google/genai/AfcUtil.java

@@ -81,6 +81,9 @@ static ImmutableList<Integer> findAfcIncompatibleToolIndexes(GenerateContentConf
       if (tool.functionDeclarations().isPresent() && !tool.functionDeclarations().get().isEmpty()) {
         incompatibleToolsIndexesBuilder.add(i);
       }
+      if (tool.mcpServers().isPresent() && !tool.mcpServers().get().isEmpty()) {
+        incompatibleToolsIndexesBuilder.add(i);
+      }
     }
 
     return incompatibleToolsIndexesBuilder.build();

src/main/java/com/google/genai/Batches.java

@@ -1862,6 +1862,13 @@ ObjectNode toolToMldev(JsonNode fromObject, ObjectNode parentObject) {
           Common.getValueByPath(fromObject, new String[] {"urlContext"}));
     }
 
+    if (Common.getValueByPath(fromObject, new String[] {"mcpServers"}) != null) {
+      Common.setValueByPath(
+          toObject,
+          new String[] {"mcpServers"},
+          Common.getValueByPath(fromObject, new String[] {"mcpServers"}));
+    }
+
     return toObject;
   }
 

src/main/java/com/google/genai/Caches.java

@@ -872,6 +872,13 @@ ObjectNode toolToMldev(JsonNode fromObject, ObjectNode parentObject) {
           Common.getValueByPath(fromObject, new String[] {"urlContext"}));
     }
 
+    if (Common.getValueByPath(fromObject, new String[] {"mcpServers"}) != null) {
+      Common.setValueByPath(
+          toObject,
+          new String[] {"mcpServers"},
+          Common.getValueByPath(fromObject, new String[] {"mcpServers"}));
+    }
+
     return toObject;
   }
 
@@ -950,6 +957,10 @@ ObjectNode toolToVertex(JsonNode fromObject, ObjectNode parentObject) {
           Common.getValueByPath(fromObject, new String[] {"urlContext"}));
     }
 
+    if (!Common.isZero(Common.getValueByPath(fromObject, new String[] {"mcpServers"}))) {
+      throw new IllegalArgumentException("mcpServers parameter is not supported in Vertex AI.");
+    }
+
     return toObject;
   }
 

src/main/java/com/google/genai/LiveConverters.java

@@ -1630,6 +1630,13 @@ ObjectNode toolToMldev(JsonNode fromObject, ObjectNode parentObject) {
           Common.getValueByPath(fromObject, new String[] {"urlContext"}));
     }
 
+    if (Common.getValueByPath(fromObject, new String[] {"mcpServers"}) != null) {
+      Common.setValueByPath(
+          toObject,
+          new String[] {"mcpServers"},
+          Common.getValueByPath(fromObject, new String[] {"mcpServers"}));
+    }
+
     return toObject;
   }
 
@@ -1708,6 +1715,10 @@ ObjectNode toolToVertex(JsonNode fromObject, ObjectNode parentObject) {
           Common.getValueByPath(fromObject, new String[] {"urlContext"}));
     }
 
+    if (!Common.isZero(Common.getValueByPath(fromObject, new String[] {"mcpServers"}))) {
+      throw new IllegalArgumentException("mcpServers parameter is not supported in Vertex AI.");
+    }
+
     return toObject;
   }
 

src/main/java/com/google/genai/Models.java

@@ -4573,6 +4573,13 @@ ObjectNode toolToMldev(JsonNode fromObject, ObjectNode parentObject, JsonNode ro
           Common.getValueByPath(fromObject, new String[] {"urlContext"}));
     }
 
+    if (Common.getValueByPath(fromObject, new String[] {"mcpServers"}) != null) {
+      Common.setValueByPath(
+          toObject,
+          new String[] {"mcpServers"},
+          Common.getValueByPath(fromObject, new String[] {"mcpServers"}));
+    }
+
     return toObject;
   }
 
@@ -4652,6 +4659,10 @@ ObjectNode toolToVertex(JsonNode fromObject, ObjectNode parentObject, JsonNode r
           Common.getValueByPath(fromObject, new String[] {"urlContext"}));
     }
 
+    if (!Common.isZero(Common.getValueByPath(fromObject, new String[] {"mcpServers"}))) {
+      throw new IllegalArgumentException("mcpServers parameter is not supported in Vertex AI.");
+    }
+
     return toObject;
   }
 

src/main/java/com/google/genai/TokensConverters.java

@@ -611,6 +611,13 @@ ObjectNode toolToMldev(JsonNode fromObject, ObjectNode parentObject) {
           Common.getValueByPath(fromObject, new String[] {"urlContext"}));
     }
 
+    if (Common.getValueByPath(fromObject, new String[] {"mcpServers"}) != null) {
+      Common.setValueByPath(
+          toObject,
+          new String[] {"mcpServers"},
+          Common.getValueByPath(fromObject, new String[] {"mcpServers"}));
+    }
+
     return toObject;
   }
 }

src/main/java/com/google/genai/types/McpServer.java

@@ -0,0 +1,119 @@
+/*
+ * Copyright 2025 Google LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+// Auto-generated code. Do not edit.
+
+package com.google.genai.types;
+
+import com.fasterxml.jackson.annotation.JsonCreator;
+import com.fasterxml.jackson.annotation.JsonProperty;
+import com.fasterxml.jackson.databind.annotation.JsonDeserialize;
+import com.google.auto.value.AutoValue;
+import com.google.errorprone.annotations.CanIgnoreReturnValue;
+import com.google.genai.JsonSerializable;
+import java.util.Optional;
+
+/**
+ * A MCPServer is a server that can be called by the model to perform actions. It is a server that
+ * implements the MCP protocol. Next ID: 5. This data type is not supported in Vertex AI.
+ */
+@AutoValue
+@JsonDeserialize(builder = McpServer.Builder.class)
+public abstract class McpServer extends JsonSerializable {
+  /** The name of the MCPServer. */
+  @JsonProperty("name")
+  public abstract Optional<String> name();
+
+  /** A transport that can stream HTTP requests and responses. */
+  @JsonProperty("streamableHttpTransport")
+  public abstract Optional<StreamableHttpTransport> streamableHttpTransport();
+
+  /** Instantiates a builder for McpServer. */
+  @ExcludeFromGeneratedCoverageReport
+  public static Builder builder() {
+    return new AutoValue_McpServer.Builder();
+  }
+
+  /** Creates a builder with the same values as this instance. */
+  public abstract Builder toBuilder();
+
+  /** Builder for McpServer. */
+  @AutoValue.Builder
+  public abstract static class Builder {
+    /** For internal usage. Please use `McpServer.builder()` for instantiation. */
+    @JsonCreator
+    private static Builder create() {
+      return new AutoValue_McpServer.Builder();
+    }
+
+    /**
+     * Setter for name.
+     *
+     * <p>name: The name of the MCPServer.
+     */
+    @JsonProperty("name")
+    public abstract Builder name(String name);
+
+    @ExcludeFromGeneratedCoverageReport
+    abstract Builder name(Optional<String> name);
+
+    /** Clears the value of name field. */
+    @ExcludeFromGeneratedCoverageReport
+    @CanIgnoreReturnValue
+    public Builder clearName() {
+      return name(Optional.empty());
+    }
+
+    /**
+     * Setter for streamableHttpTransport.
+     *
+     * <p>streamableHttpTransport: A transport that can stream HTTP requests and responses.
+     */
+    @JsonProperty("streamableHttpTransport")
+    public abstract Builder streamableHttpTransport(
+        StreamableHttpTransport streamableHttpTransport);
+
+    /**
+     * Setter for streamableHttpTransport builder.
+     *
+     * <p>streamableHttpTransport: A transport that can stream HTTP requests and responses.
+     */
+    @CanIgnoreReturnValue
+    public Builder streamableHttpTransport(
+        StreamableHttpTransport.Builder streamableHttpTransportBuilder) {
+      return streamableHttpTransport(streamableHttpTransportBuilder.build());
+    }
+
+    @ExcludeFromGeneratedCoverageReport
+    abstract Builder streamableHttpTransport(
+        Optional<StreamableHttpTransport> streamableHttpTransport);
+
+    /** Clears the value of streamableHttpTransport field. */
+    @ExcludeFromGeneratedCoverageReport
+    @CanIgnoreReturnValue
+    public Builder clearStreamableHttpTransport() {
+      return streamableHttpTransport(Optional.empty());
+    }
+
+    public abstract McpServer build();
+  }
+
+  /** Deserializes a JSON string to a McpServer object. */
+  @ExcludeFromGeneratedCoverageReport
+  public static McpServer fromJson(String jsonString) {
+    return JsonSerializable.fromJsonString(jsonString, McpServer.class);
+  }
+}