diff --git a/client/transport/rest/src/main/java/org/a2aproject/sdk/client/transport/rest/RestTransport.java b/client/transport/rest/src/main/java/org/a2aproject/sdk/client/transport/rest/RestTransport.java
index b716fc934..1f8f5c3e3 100644
--- a/client/transport/rest/src/main/java/org/a2aproject/sdk/client/transport/rest/RestTransport.java
+++ b/client/transport/rest/src/main/java/org/a2aproject/sdk/client/transport/rest/RestTransport.java
@@ -22,6 +22,7 @@
 import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.atomic.AtomicReference;
 import java.util.function.Consumer;
+import java.util.logging.Level;
 import java.util.logging.Logger;
 
 import com.google.protobuf.InvalidProtocolBufferException;
@@ -36,6 +37,7 @@
 import org.a2aproject.sdk.client.transport.spi.interceptors.ClientCallContext;
 import org.a2aproject.sdk.client.transport.spi.interceptors.ClientCallInterceptor;
 import org.a2aproject.sdk.client.transport.spi.interceptors.PayloadAndHeaders;
+import org.a2aproject.sdk.grpc.utils.ProtoJsonUtils;
 import org.a2aproject.sdk.grpc.utils.ProtoUtils;
 import org.a2aproject.sdk.jsonrpc.common.json.JsonProcessingException;
 import org.a2aproject.sdk.jsonrpc.common.json.JsonUtil;
@@ -431,19 +433,24 @@ private String sendPostRequest(String url, PayloadAndHeaders payloadAndHeaders)
         A2AHttpClient.PostBuilder builder = createPostBuilder(url, payloadAndHeaders);
         A2AHttpResponse response = builder.post();
         if (!response.success()) {
-            log.fine("Error on POST processing " + JsonFormat.printer().print((MessageOrBuilder) payloadAndHeaders.getPayload()));
+            if (log.isLoggable(Level.FINE)) {
+                log.fine("Error on POST processing " + ProtoJsonUtils.toJson(JsonFormat.printer(), (MessageOrBuilder) payloadAndHeaders.getPayload()));
+            }
             throw RestErrorMapper.mapRestError(response);
         }
         return response.body();
     }
 
     private A2AHttpClient.PostBuilder createPostBuilder(String url, PayloadAndHeaders payloadAndHeaders) throws JsonProcessingException, InvalidProtocolBufferException {
-        log.fine(JsonFormat.printer().print((MessageOrBuilder) payloadAndHeaders.getPayload()));
+        String body = ProtoJsonUtils.toJson(JsonFormat.printer(), (MessageOrBuilder) payloadAndHeaders.getPayload());
+        if (log.isLoggable(Level.FINE)) {
+            log.fine(body);
+        }
         A2AHttpClient.PostBuilder postBuilder = httpClient.createPost()
                 .url(url)
                 .addHeader("Content-Type", "application/json")
                 .addHeader(A2AHeaders.A2A_VERSION, AgentInterface.CURRENT_PROTOCOL_VERSION)
-                .body(JsonFormat.printer().print((MessageOrBuilder) payloadAndHeaders.getPayload()));
+                .body(body);
 
         if (payloadAndHeaders.getHeaders() != null) {
             for (Map.Entry<String, String> entry : payloadAndHeaders.getHeaders().entrySet()) {
diff --git a/common/pom.xml b/common/pom.xml
index fb3d3a01f..04104dd01 100644
--- a/common/pom.xml
+++ b/common/pom.xml
@@ -21,6 +21,11 @@
             <groupId>org.slf4j</groupId>
             <artifactId>slf4j-api</artifactId>
         </dependency>
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter-api</artifactId>
+            <scope>test</scope>
+        </dependency>
     </dependencies>
 
 </project>
\ No newline at end of file
diff --git a/common/src/main/java/org/a2aproject/sdk/util/HtmlEscapeUtils.java b/common/src/main/java/org/a2aproject/sdk/util/HtmlEscapeUtils.java
new file mode 100644
index 000000000..a36e3058f
--- /dev/null
+++ b/common/src/main/java/org/a2aproject/sdk/util/HtmlEscapeUtils.java
@@ -0,0 +1,31 @@
+package org.a2aproject.sdk.util;
+
+/**
+ * Utilities for removing HTML escaping applied by Gson's {@link com.google.gson.stream.JsonWriter}
+ * when {@code htmlSafe} is enabled (the default).
+ */
+public final class HtmlEscapeUtils {
+
+    private HtmlEscapeUtils() {
+    }
+
+    /**
+     * Removes HTML escaping applied by Gson's {@link com.google.gson.stream.JsonWriter} when
+     * {@code htmlSafe} is enabled (the default). Restores literal
+     * {@code <}, {@code >}, {@code &}, {@code =}, and {@code '}.
+     * <p>
+     * Gson also escapes U+2028 (line separator) and U+2029 (paragraph separator) in HTML-safe
+     * mode, but those are left as-is because they are valid JSON encodings that preserve the
+     * original characters without data corruption.
+     *
+     * @param json the JSON string potentially containing HTML-escaped sequences
+     * @return the JSON string with literal characters restored
+     */
+    public static String removeHtmlEscaping(String json) {
+        return json.replace("\\u003c", "<")
+                .replace("\\u003e", ">")
+                .replace("\\u0026", "&")
+                .replace("\\u003d", "=")
+                .replace("\\u0027", "'");
+    }
+}
diff --git a/common/src/test/java/org/a2aproject/sdk/util/HtmlEscapeUtilsTest.java b/common/src/test/java/org/a2aproject/sdk/util/HtmlEscapeUtilsTest.java
new file mode 100644
index 000000000..ff7191e28
--- /dev/null
+++ b/common/src/test/java/org/a2aproject/sdk/util/HtmlEscapeUtilsTest.java
@@ -0,0 +1,45 @@
+package org.a2aproject.sdk.util;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import org.junit.jupiter.api.Test;
+
+public class HtmlEscapeUtilsTest {
+
+    @Test
+    public void removeHtmlEscaping_restoresAngleBrackets() {
+        assertEquals("<event-topic>", HtmlEscapeUtils.removeHtmlEscaping("\\u003cevent-topic\\u003e"));
+    }
+
+    @Test
+    public void removeHtmlEscaping_restoresAmpersand() {
+        assertEquals("foo&bar", HtmlEscapeUtils.removeHtmlEscaping("foo\\u0026bar"));
+    }
+
+    @Test
+    public void removeHtmlEscaping_restoresEquals() {
+        assertEquals("a=b", HtmlEscapeUtils.removeHtmlEscaping("a\\u003db"));
+    }
+
+    @Test
+    public void removeHtmlEscaping_restoresApostrophe() {
+        assertEquals("it's", HtmlEscapeUtils.removeHtmlEscaping("it\\u0027s"));
+    }
+
+    @Test
+    public void removeHtmlEscaping_handlesMultipleEscapes() {
+        assertEquals("<tag>&</tag>",
+                HtmlEscapeUtils.removeHtmlEscaping("\\u003ctag\\u003e\\u0026\\u003c/tag\\u003e"));
+    }
+
+    @Test
+    public void removeHtmlEscaping_leavesRegularJsonUntouched() {
+        String json = "{\"key\": \"value\", \"num\": 42}";
+        assertEquals(json, HtmlEscapeUtils.removeHtmlEscaping(json));
+    }
+
+    @Test
+    public void removeHtmlEscaping_handlesEmptyString() {
+        assertEquals("", HtmlEscapeUtils.removeHtmlEscaping(""));
+    }
+}
diff --git a/compat-0.3/client/transport/rest/src/main/java/org/a2aproject/sdk/compat03/client/transport/rest/RestTransport_v0_3.java b/compat-0.3/client/transport/rest/src/main/java/org/a2aproject/sdk/compat03/client/transport/rest/RestTransport_v0_3.java
index 6ff2d560d..e4621ba7c 100644
--- a/compat-0.3/client/transport/rest/src/main/java/org/a2aproject/sdk/compat03/client/transport/rest/RestTransport_v0_3.java
+++ b/compat-0.3/client/transport/rest/src/main/java/org/a2aproject/sdk/compat03/client/transport/rest/RestTransport_v0_3.java
@@ -41,6 +41,7 @@
 import org.a2aproject.sdk.compat03.spec.Task_v0_3;
 import org.a2aproject.sdk.compat03.spec.TaskIdParams_v0_3;
 import org.a2aproject.sdk.compat03.spec.TaskQueryParams_v0_3;
+import org.a2aproject.sdk.compat03.grpc.utils.ProtoJsonUtils_v0_3;
 import org.a2aproject.sdk.compat03.grpc.utils.ProtoUtils_v0_3;
 import org.a2aproject.sdk.compat03.spec.A2AClientError_v0_3;
 import org.a2aproject.sdk.compat03.spec.SendStreamingMessageRequest_v0_3;
@@ -49,6 +50,7 @@
 import java.io.IOException;
 import java.util.Collections;
 import java.util.List;
+import java.util.logging.Level;
 import java.util.logging.Logger;
 import java.util.Map;
 import java.util.concurrent.CompletableFuture;
@@ -375,18 +377,23 @@ private String sendPostRequest(String url, PayloadAndHeaders_v0_3 payloadAndHead
         A2AHttpClient.PostBuilder builder = createPostBuilder(url, payloadAndHeaders);
         A2AHttpResponse response = builder.post();
         if (!response.success()) {
-            log.fine("Error on POST processing " + JsonFormat.printer().print((MessageOrBuilder) payloadAndHeaders.getPayload()));
+            if (log.isLoggable(Level.FINE)) {
+                log.fine("Error on POST processing " + ProtoJsonUtils_v0_3.toJson(JsonFormat.printer(), (MessageOrBuilder) payloadAndHeaders.getPayload()));
+            }
             throw RestErrorMapper_v0_3.mapRestError(response);
         }
         return response.body();
     }
 
     private A2AHttpClient.PostBuilder createPostBuilder(String url, PayloadAndHeaders_v0_3 payloadAndHeaders) throws JsonProcessingException_v0_3, InvalidProtocolBufferException {
-        log.fine(JsonFormat.printer().print((MessageOrBuilder) payloadAndHeaders.getPayload()));
+        String body = ProtoJsonUtils_v0_3.toJson(JsonFormat.printer(), (MessageOrBuilder) payloadAndHeaders.getPayload());
+        if (log.isLoggable(Level.FINE)) {
+            log.fine(body);
+        }
         A2AHttpClient.PostBuilder postBuilder = httpClient.createPost()
                 .url(url)
                 .addHeader("Content-Type", "application/json")
-                .body(JsonFormat.printer().print((MessageOrBuilder) payloadAndHeaders.getPayload()));
+                .body(body);
 
         if (payloadAndHeaders.getHeaders() != null) {
             for (Map.Entry<String, String> entry : payloadAndHeaders.getHeaders().entrySet()) {
diff --git a/compat-0.3/spec-grpc/pom.xml b/compat-0.3/spec-grpc/pom.xml
index b591fe3bb..ead70420f 100644
--- a/compat-0.3/spec-grpc/pom.xml
+++ b/compat-0.3/spec-grpc/pom.xml
@@ -48,6 +48,11 @@
             <groupId>com.google.api.grpc</groupId>
             <artifactId>proto-google-common-protos</artifactId>
         </dependency>
+        <dependency>
+            <groupId>com.google.protobuf</groupId>
+            <artifactId>protobuf-java-util</artifactId>
+            <scope>provided</scope>
+        </dependency>
 
         <!-- Annotation dependency for generated code -->
         <dependency>
diff --git a/compat-0.3/spec-grpc/src/main/java/org/a2aproject/sdk/compat03/grpc/utils/ProtoJsonUtils_v0_3.java b/compat-0.3/spec-grpc/src/main/java/org/a2aproject/sdk/compat03/grpc/utils/ProtoJsonUtils_v0_3.java
new file mode 100644
index 000000000..697c22c45
--- /dev/null
+++ b/compat-0.3/spec-grpc/src/main/java/org/a2aproject/sdk/compat03/grpc/utils/ProtoJsonUtils_v0_3.java
@@ -0,0 +1,40 @@
+package org.a2aproject.sdk.compat03.grpc.utils;
+
+import com.google.protobuf.InvalidProtocolBufferException;
+import com.google.protobuf.MessageOrBuilder;
+import com.google.protobuf.util.JsonFormat;
+import org.a2aproject.sdk.util.HtmlEscapeUtils;
+import org.jspecify.annotations.Nullable;
+
+/**
+ * Protobuf-to-JSON serialization without HTML escaping.
+ * <p>
+ * {@link JsonFormat#printer()} delegates to Gson's {@link com.google.gson.stream.JsonWriter}
+ * which HTML-escapes {@code <}, {@code >}, and {@code &} by default. This utility
+ * removes those escape sequences via {@link HtmlEscapeUtils#removeHtmlEscaping(String)}.
+ * <p>
+ * Intentionally duplicated from {@code org.a2aproject.sdk.grpc.utils.ProtoJsonUtils}
+ * to maintain v0.3 module isolation (compat-0.3/spec-grpc cannot depend on spec-grpc).
+ */
+public final class ProtoJsonUtils_v0_3 {
+
+    private ProtoJsonUtils_v0_3() {
+    }
+
+    /**
+     * Serializes a protobuf message to JSON using the supplied printer,
+     * then removes HTML escaping.
+     *
+     * @param printer the configured {@link JsonFormat.Printer} (callers choose options
+     *                such as {@code alwaysPrintFieldsWithNoPresence()} or
+     *                {@code omittingInsignificantWhitespace()})
+     * @param proto   the protobuf message to serialize, or {@code null}
+     * @return JSON string without HTML-escaped characters, or empty string if proto is null
+     */
+    public static String toJson(JsonFormat.Printer printer, @Nullable MessageOrBuilder proto) throws InvalidProtocolBufferException {
+        if (proto == null) {
+            return "";
+        }
+        return HtmlEscapeUtils.removeHtmlEscaping(printer.print(proto));
+    }
+}
diff --git a/compat-0.3/spec-grpc/src/test/java/org/a2aproject/sdk/compat03/grpc/utils/ProtoJsonUtils_v0_3_Test.java b/compat-0.3/spec-grpc/src/test/java/org/a2aproject/sdk/compat03/grpc/utils/ProtoJsonUtils_v0_3_Test.java
new file mode 100644
index 000000000..7766c57a2
--- /dev/null
+++ b/compat-0.3/spec-grpc/src/test/java/org/a2aproject/sdk/compat03/grpc/utils/ProtoJsonUtils_v0_3_Test.java
@@ -0,0 +1,89 @@
+package org.a2aproject.sdk.compat03.grpc.utils;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import java.util.Collections;
+
+import com.google.protobuf.util.JsonFormat;
+
+import org.a2aproject.sdk.compat03.spec.Message_v0_3;
+import org.a2aproject.sdk.compat03.spec.MessageSendParams_v0_3;
+import org.a2aproject.sdk.compat03.spec.TextPart_v0_3;
+import org.junit.jupiter.api.Test;
+
+public class ProtoJsonUtils_v0_3_Test {
+
+    @Test
+    public void toJson_doesNotHtmlEscapeAngleBrackets() throws Exception {
+        MessageSendParams_v0_3 params = new MessageSendParams_v0_3(
+            new Message_v0_3.Builder()
+                .role(Message_v0_3.Role.USER)
+                .parts(Collections.singletonList(new TextPart_v0_3("<event-topic>")))
+                .contextId("context-1234")
+                .messageId("message-1234")
+                .build(),
+            null, null
+        );
+        var proto = ProtoUtils_v0_3.ToProto.sendMessageRequest(params);
+
+        String json = ProtoJsonUtils_v0_3.toJson(JsonFormat.printer(), proto);
+
+        assertTrue(json.contains("<event-topic>"),
+            "JSON should preserve literal '<event-topic>' but got: " + json);
+        assertFalse(json.contains("\\u003c"),
+            "JSON must not contain HTML-escaped '<' (\\u003c) but got: " + json);
+        assertFalse(json.contains("\\u003e"),
+            "JSON must not contain HTML-escaped '>' (\\u003e) but got: " + json);
+    }
+
+    @Test
+    public void toJson_doesNotHtmlEscapeAmpersand() throws Exception {
+        MessageSendParams_v0_3 params = new MessageSendParams_v0_3(
+            new Message_v0_3.Builder()
+                .role(Message_v0_3.Role.USER)
+                .parts(Collections.singletonList(new TextPart_v0_3("foo&bar")))
+                .contextId("context-1234")
+                .messageId("message-1234")
+                .build(),
+            null, null
+        );
+        var proto = ProtoUtils_v0_3.ToProto.sendMessageRequest(params);
+
+        String json = ProtoJsonUtils_v0_3.toJson(JsonFormat.printer(), proto);
+
+        assertTrue(json.contains("foo&bar"),
+            "JSON should preserve literal '&' but got: " + json);
+        assertFalse(json.contains("\\u0026"),
+            "JSON must not contain HTML-escaped '&' (\\u0026) but got: " + json);
+    }
+
+    @Test
+    public void toJson_respectsAlwaysPrintFieldsWithNoPresence() throws Exception {
+        MessageSendParams_v0_3 params = new MessageSendParams_v0_3(
+            new Message_v0_3.Builder()
+                .role(Message_v0_3.Role.USER)
+                .parts(Collections.singletonList(new TextPart_v0_3("hello")))
+                .contextId("context-1234")
+                .messageId("message-1234")
+                .build(),
+            null, null
+        );
+        var proto = ProtoUtils_v0_3.ToProto.sendMessageRequest(params);
+
+        String withDefaults = ProtoJsonUtils_v0_3.toJson(
+            JsonFormat.printer().alwaysPrintFieldsWithNoPresence(), proto);
+        String withoutDefaults = ProtoJsonUtils_v0_3.toJson(JsonFormat.printer(), proto);
+
+        assertTrue(withDefaults.length() > withoutDefaults.length(),
+            "alwaysPrintFieldsWithNoPresence should produce more fields, got:\n  with: " + withDefaults + "\n  without: " + withoutDefaults);
+    }
+
+    @Test
+    public void toJson_returnsEmptyStringForNull() throws Exception {
+        String result = ProtoJsonUtils_v0_3.toJson(JsonFormat.printer(), null);
+
+        assertEquals("", result);
+    }
+}
diff --git a/compat-0.3/transport/rest/src/main/java/org/a2aproject/sdk/compat03/transport/rest/handler/RestHandler_v0_3.java b/compat-0.3/transport/rest/src/main/java/org/a2aproject/sdk/compat03/transport/rest/handler/RestHandler_v0_3.java
index 8b08c6952..174ba355e 100644
--- a/compat-0.3/transport/rest/src/main/java/org/a2aproject/sdk/compat03/transport/rest/handler/RestHandler_v0_3.java
+++ b/compat-0.3/transport/rest/src/main/java/org/a2aproject/sdk/compat03/transport/rest/handler/RestHandler_v0_3.java
@@ -6,6 +6,7 @@
 import com.google.gson.JsonSyntaxException;
 import com.google.protobuf.InvalidProtocolBufferException;
 import com.google.protobuf.util.JsonFormat;
+import org.a2aproject.sdk.compat03.grpc.utils.ProtoJsonUtils_v0_3;
 import org.a2aproject.sdk.compat03.grpc.utils.ProtoUtils_v0_3;
 import jakarta.enterprise.context.ApplicationScoped;
 import jakarta.inject.Inject;
@@ -267,7 +268,7 @@ private void validate(String json) {
 
     private HTTPRestResponse createSuccessResponse(int statusCode, com.google.protobuf.Message.Builder builder) {
         try {
-            String jsonBody = JsonFormat.printer().print(builder);
+            String jsonBody = ProtoJsonUtils_v0_3.toJson(JsonFormat.printer(), builder);
             return new HTTPRestResponse(statusCode, "application/json", jsonBody);
         } catch (InvalidProtocolBufferException e) {
             return createErrorResponse(new InternalError_v0_3("Failed to serialize response: " + e.getMessage()));
@@ -307,7 +308,8 @@ public void onSubscribe(Flow.Subscription subscription) {
                     @Override
                     public void onNext(StreamingEventKind_v0_3 item) {
                         try {
-                            String payload = JsonFormat.printer().omittingInsignificantWhitespace().print(ProtoUtils_v0_3.ToProto.taskOrMessageStream(item));
+                            String payload = ProtoJsonUtils_v0_3.toJson(
+                                    JsonFormat.printer().omittingInsignificantWhitespace(), ProtoUtils_v0_3.ToProto.taskOrMessageStream(item));
                             tube.send(payload);
                             if (subscription != null) {
                                 subscription.request(1);
diff --git a/spec-grpc/src/main/java/org/a2aproject/sdk/grpc/utils/JSONRPCUtils.java b/spec-grpc/src/main/java/org/a2aproject/sdk/grpc/utils/JSONRPCUtils.java
index 2abbe0190..4e0456516 100644
--- a/spec-grpc/src/main/java/org/a2aproject/sdk/grpc/utils/JSONRPCUtils.java
+++ b/spec-grpc/src/main/java/org/a2aproject/sdk/grpc/utils/JSONRPCUtils.java
@@ -576,7 +576,8 @@ public static String toJsonRPCRequest(@Nullable String requestId, String method,
                 output.name("method").value(method);
             }
             if (payload != null) {
-                String resultValue = JsonFormat.printer().alwaysPrintFieldsWithNoPresence().omittingInsignificantWhitespace().print(payload);
+                String resultValue = ProtoJsonUtils.toJson(
+                        JsonFormat.printer().alwaysPrintFieldsWithNoPresence().omittingInsignificantWhitespace(), payload);
                 output.name("params").jsonValue(resultValue);
             }
             output.endObject();
@@ -593,7 +594,8 @@ public static String toJsonRPCResultResponse(@Nullable Object requestId, com.goo
             output.beginObject();
             output.name("jsonrpc").value("2.0");
             JsonUtil.writeJsonRpcId(output, requestId);
-            String resultValue = JsonFormat.printer().alwaysPrintFieldsWithNoPresence().omittingInsignificantWhitespace().print(builder);
+            String resultValue = ProtoJsonUtils.toJson(
+                    JsonFormat.printer().alwaysPrintFieldsWithNoPresence().omittingInsignificantWhitespace(), builder);
             output.name("result").jsonValue(resultValue);
             output.endObject();
             return result.toString();
diff --git a/spec-grpc/src/main/java/org/a2aproject/sdk/grpc/utils/ProtoJsonUtils.java b/spec-grpc/src/main/java/org/a2aproject/sdk/grpc/utils/ProtoJsonUtils.java
new file mode 100644
index 000000000..42809dda3
--- /dev/null
+++ b/spec-grpc/src/main/java/org/a2aproject/sdk/grpc/utils/ProtoJsonUtils.java
@@ -0,0 +1,37 @@
+package org.a2aproject.sdk.grpc.utils;
+
+import com.google.protobuf.InvalidProtocolBufferException;
+import com.google.protobuf.MessageOrBuilder;
+import com.google.protobuf.util.JsonFormat;
+import org.a2aproject.sdk.util.HtmlEscapeUtils;
+import org.jspecify.annotations.Nullable;
+
+/**
+ * Protobuf-to-JSON serialization without HTML escaping.
+ * <p>
+ * {@link JsonFormat#printer()} delegates to Gson's {@link com.google.gson.stream.JsonWriter}
+ * which HTML-escapes {@code <}, {@code >}, and {@code &} by default. This utility
+ * removes those escape sequences via {@link HtmlEscapeUtils#removeHtmlEscaping(String)}.
+ */
+public final class ProtoJsonUtils {
+
+    private ProtoJsonUtils() {
+    }
+
+    /**
+     * Serializes a protobuf message to JSON using the supplied printer,
+     * then removes HTML escaping.
+     *
+     * @param printer the configured {@link JsonFormat.Printer} (callers choose options
+     *                such as {@code alwaysPrintFieldsWithNoPresence()} or
+     *                {@code omittingInsignificantWhitespace()})
+     * @param proto   the protobuf message to serialize, or {@code null}
+     * @return JSON string without HTML-escaped characters, or empty string if proto is null
+     */
+    public static String toJson(JsonFormat.Printer printer, @Nullable MessageOrBuilder proto) throws InvalidProtocolBufferException {
+        if (proto == null) {
+            return "";
+        }
+        return HtmlEscapeUtils.removeHtmlEscaping(printer.print(proto));
+    }
+}
diff --git a/spec-grpc/src/test/java/org/a2aproject/sdk/grpc/utils/JSONRPCUtilsTest.java b/spec-grpc/src/test/java/org/a2aproject/sdk/grpc/utils/JSONRPCUtilsTest.java
index 4193fa725..67ffc203c 100644
--- a/spec-grpc/src/test/java/org/a2aproject/sdk/grpc/utils/JSONRPCUtilsTest.java
+++ b/spec-grpc/src/test/java/org/a2aproject/sdk/grpc/utils/JSONRPCUtilsTest.java
@@ -2,18 +2,23 @@
 
 import static org.a2aproject.sdk.grpc.utils.JSONRPCUtils.ERROR_MESSAGE;
 import static org.a2aproject.sdk.spec.A2AMethods.GET_TASK_PUSH_NOTIFICATION_CONFIG_METHOD;
+import static org.a2aproject.sdk.spec.A2AMethods.SEND_MESSAGE_METHOD;
 import static org.a2aproject.sdk.spec.A2AMethods.SET_TASK_PUSH_NOTIFICATION_CONFIG_METHOD;
 import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
 import static org.junit.jupiter.api.Assertions.assertInstanceOf;
 import static org.junit.jupiter.api.Assertions.assertNotNull;
 import static org.junit.jupiter.api.Assertions.assertThrows;
 import static org.junit.jupiter.api.Assertions.assertTrue;
 import static org.junit.jupiter.api.Assertions.fail;
 
+import java.util.Collections;
+
 import com.google.gson.JsonArray;
 import com.google.gson.JsonParser;
 import com.google.gson.JsonSyntaxException;
 
+import org.a2aproject.sdk.grpc.SendMessageResponse;
 import org.a2aproject.sdk.jsonrpc.common.json.InvalidParamsJsonMappingException;
 import org.a2aproject.sdk.jsonrpc.common.json.JsonMappingException;
 import org.a2aproject.sdk.jsonrpc.common.json.JsonProcessingException;
@@ -24,8 +29,11 @@
 import org.a2aproject.sdk.jsonrpc.common.wrappers.GetTaskPushNotificationConfigResponse;
 import org.a2aproject.sdk.spec.InvalidParamsError;
 import org.a2aproject.sdk.spec.JSONParseError;
+import org.a2aproject.sdk.spec.Message;
+import org.a2aproject.sdk.spec.MessageSendParams;
 import org.a2aproject.sdk.spec.TaskNotFoundError;
 import org.a2aproject.sdk.spec.TaskPushNotificationConfig;
+import org.a2aproject.sdk.spec.TextPart;
 import org.a2aproject.sdk.util.ErrorDetail;
 import org.junit.jupiter.api.Test;
 
@@ -485,4 +493,51 @@ public void testToJsonRPCErrorResponse_RoundTrip() throws Exception {
         assertEquals("Custom message", response.getError().getMessage());
     }
 
+    @Test
+    public void testToJsonRPCRequest_doesNotHtmlEscapeAngleBrackets() {
+        // Reproduce issue #892: HTML special characters in message text were escaped
+        // to Unicode sequences (< for <, > for >) by JsonFormat.printer().
+        MessageSendParams params = new MessageSendParams(
+            Message.builder()
+                .role(Message.Role.ROLE_USER)
+                .parts(Collections.singletonList(new TextPart("<event-topic>")))
+                .contextId("context-1234")
+                .messageId("message-1234")
+                .build(),
+            null, null
+        );
+        org.a2aproject.sdk.grpc.SendMessageRequest protoRequest =
+            ProtoUtils.ToProto.sendMessageRequest(params);
+
+        String json = JSONRPCUtils.toJsonRPCRequest("test-id", SEND_MESSAGE_METHOD, protoRequest);
+
+        assertTrue(json.contains("<event-topic>"),
+            "JSON should preserve literal '<event-topic>' but got: " + json);
+        assertFalse(json.contains("\\u003c"),
+            "JSON must not contain HTML-escaped '<' (\\u003c) but got: " + json);
+        assertFalse(json.contains("\\u003e"),
+            "JSON must not contain HTML-escaped '>' (\\u003e) but got: " + json);
+    }
+
+    @Test
+    public void testToJsonRPCResultResponse_doesNotHtmlEscapeAngleBrackets() {
+        // Reproduce issue #892: server responses must also send literal angle brackets.
+        Message message = Message.builder()
+            .role(Message.Role.ROLE_AGENT)
+            .parts(Collections.singletonList(new TextPart("<result>")))
+            .contextId("context-1234")
+            .messageId("message-5678")
+            .build();
+        SendMessageResponse protoResponse = ProtoUtils.ToProto.taskOrMessage(message);
+
+        String json = JSONRPCUtils.toJsonRPCResultResponse("test-id", protoResponse);
+
+        assertTrue(json.contains("<result>"),
+            "JSON should preserve literal '<result>' but got: " + json);
+        assertFalse(json.contains("\\u003c"),
+            "JSON must not contain HTML-escaped '<' (\\u003c) but got: " + json);
+        assertFalse(json.contains("\\u003e"),
+            "JSON must not contain HTML-escaped '>' (\\u003e) but got: " + json);
+    }
+
 }
diff --git a/spec-grpc/src/test/java/org/a2aproject/sdk/grpc/utils/ProtoJsonUtilsTest.java b/spec-grpc/src/test/java/org/a2aproject/sdk/grpc/utils/ProtoJsonUtilsTest.java
new file mode 100644
index 000000000..961af246d
--- /dev/null
+++ b/spec-grpc/src/test/java/org/a2aproject/sdk/grpc/utils/ProtoJsonUtilsTest.java
@@ -0,0 +1,89 @@
+package org.a2aproject.sdk.grpc.utils;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import java.util.Collections;
+
+import com.google.protobuf.util.JsonFormat;
+
+import org.a2aproject.sdk.spec.Message;
+import org.a2aproject.sdk.spec.MessageSendParams;
+import org.a2aproject.sdk.spec.TextPart;
+import org.junit.jupiter.api.Test;
+
+public class ProtoJsonUtilsTest {
+
+    @Test
+    public void toJson_doesNotHtmlEscapeAngleBrackets() throws Exception {
+        MessageSendParams params = new MessageSendParams(
+            Message.builder()
+                .role(Message.Role.ROLE_USER)
+                .parts(Collections.singletonList(new TextPart("<event-topic>")))
+                .contextId("context-1234")
+                .messageId("message-1234")
+                .build(),
+            null, null
+        );
+        var proto = ProtoUtils.ToProto.sendMessageRequest(params);
+
+        String json = ProtoJsonUtils.toJson(JsonFormat.printer(), proto);
+
+        assertTrue(json.contains("<event-topic>"),
+            "JSON should preserve literal '<event-topic>' but got: " + json);
+        assertFalse(json.contains("\\u003c"),
+            "JSON must not contain HTML-escaped '<' (\\u003c) but got: " + json);
+        assertFalse(json.contains("\\u003e"),
+            "JSON must not contain HTML-escaped '>' (\\u003e) but got: " + json);
+    }
+
+    @Test
+    public void toJson_doesNotHtmlEscapeAmpersand() throws Exception {
+        MessageSendParams params = new MessageSendParams(
+            Message.builder()
+                .role(Message.Role.ROLE_USER)
+                .parts(Collections.singletonList(new TextPart("foo&bar")))
+                .contextId("context-1234")
+                .messageId("message-1234")
+                .build(),
+            null, null
+        );
+        var proto = ProtoUtils.ToProto.sendMessageRequest(params);
+
+        String json = ProtoJsonUtils.toJson(JsonFormat.printer(), proto);
+
+        assertTrue(json.contains("foo&bar"),
+            "JSON should preserve literal '&' but got: " + json);
+        assertFalse(json.contains("\\u0026"),
+            "JSON must not contain HTML-escaped '&' (\\u0026) but got: " + json);
+    }
+
+    @Test
+    public void toJson_respectsAlwaysPrintFieldsWithNoPresence() throws Exception {
+        MessageSendParams params = new MessageSendParams(
+            Message.builder()
+                .role(Message.Role.ROLE_USER)
+                .parts(Collections.singletonList(new TextPart("hello")))
+                .contextId("context-1234")
+                .messageId("message-1234")
+                .build(),
+            null, null
+        );
+        var proto = ProtoUtils.ToProto.sendMessageRequest(params);
+
+        String withDefaults = ProtoJsonUtils.toJson(
+            JsonFormat.printer().alwaysPrintFieldsWithNoPresence(), proto);
+        String withoutDefaults = ProtoJsonUtils.toJson(JsonFormat.printer(), proto);
+
+        assertTrue(withDefaults.length() > withoutDefaults.length(),
+            "alwaysPrintFieldsWithNoPresence should produce more fields, got:\n  with: " + withDefaults + "\n  without: " + withoutDefaults);
+    }
+
+    @Test
+    public void toJson_returnsEmptyStringForNull() throws Exception {
+        String result = ProtoJsonUtils.toJson(JsonFormat.printer(), null);
+
+        assertEquals("", result);
+    }
+}
diff --git a/transport/rest/src/main/java/org/a2aproject/sdk/transport/rest/handler/RestHandler.java b/transport/rest/src/main/java/org/a2aproject/sdk/transport/rest/handler/RestHandler.java
index 84442cc8d..a22fdce7c 100644
--- a/transport/rest/src/main/java/org/a2aproject/sdk/transport/rest/handler/RestHandler.java
+++ b/transport/rest/src/main/java/org/a2aproject/sdk/transport/rest/handler/RestHandler.java
@@ -25,6 +25,7 @@
 import com.google.protobuf.InvalidProtocolBufferException;
 import com.google.protobuf.util.JsonFormat;
 import mutiny.zero.ZeroPublisher;
+import org.a2aproject.sdk.grpc.utils.ProtoJsonUtils;
 import org.a2aproject.sdk.grpc.utils.ProtoUtils;
 import org.a2aproject.sdk.util.ErrorDetail;
 import org.a2aproject.sdk.jsonrpc.common.json.JsonProcessingException;
@@ -666,7 +667,7 @@ private void validate(String json) {
     private HTTPRestResponse createSuccessResponse(int statusCode, com.google.protobuf.Message.Builder builder) {
         try {
             // Include default value fields to ensure empty arrays, zeros, etc. are present in JSON
-            String jsonBody = JsonFormat.printer().alwaysPrintFieldsWithNoPresence().print(builder);
+            String jsonBody = ProtoJsonUtils.toJson(JsonFormat.printer().alwaysPrintFieldsWithNoPresence(), builder);
             return new HTTPRestResponse(statusCode, APPLICATION_JSON, jsonBody);
         } catch (InvalidProtocolBufferException e) {
             return createErrorResponse(new InternalError("Failed to serialize response: " + e.getMessage()));
@@ -717,7 +718,8 @@ public void onSubscribe(Flow.Subscription subscription) {
                     public void onNext(StreamingEventKind item) {
                         log.log(Level.FINE, "REST: onNext called with event: {0}", item.getClass().getSimpleName());
                         try {
-                            String payload = JsonFormat.printer().omittingInsignificantWhitespace().print(ProtoUtils.ToProto.taskOrMessageStream(item));
+                            String payload = ProtoJsonUtils.toJson(
+                                    JsonFormat.printer().omittingInsignificantWhitespace(), ProtoUtils.ToProto.taskOrMessageStream(item));
                             log.log(Level.FINE, "REST: Converted to JSON, sending via tube: {0}", payload.substring(0, Math.min(100, payload.length())));
                             tube.send(payload);
                             log.log(Level.FINE, "REST: tube.send() completed, requesting next event from EventConsumer");