diff --git a/Cargo.lock b/Cargo.lock
index 9ebd3d4..e986e5c 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -138,9 +138,8 @@ dependencies = [
 
 [[package]]
 name = "agent-client-protocol-schema"
-version = "1.1.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "ac542aba230234b1591ace7286a47c0514fe3efc3037d43296bde31ba7ee5728"
+version = "1.2.0"
+source = "git+https://github.com/daniel-agentee/agent-client-protocol?rev=064ee1ffe194cdb14e1d45d66875ce74a14933c3#064ee1ffe194cdb14e1d45d66875ce74a14933c3"
 dependencies = [
  "anyhow",
  "derive_more",
diff --git a/Cargo.toml b/Cargo.toml
index 8db2927..d429488 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -37,7 +37,7 @@ agent-client-protocol-trace-viewer = { path = "src/agent-client-protocol-trace-v
 yopo = { package = "agent-client-protocol-yopo", path = "src/yopo" }
 
 # Protocol
-agent-client-protocol-schema = { version = "=1.1.0", features = ["tracing"] }
+agent-client-protocol-schema = { version = "=1.2.0", features = ["tracing"] }
 
 # Core async runtime
 tokio = { version = "1.52", default-features = false }
@@ -113,3 +113,7 @@ struct_field_names = "allow"
 too_many_lines = "allow"
 type_complexity = "allow"
 wildcard_imports = "allow"
+
+[patch.crates-io]
+# Temporary: consume session/setTitle schema types before they are released.
+agent-client-protocol-schema = { git = "https://github.com/daniel-agentee/agent-client-protocol", rev = "064ee1ffe194cdb14e1d45d66875ce74a14933c3" }
diff --git a/src/agent-client-protocol-test/src/testy.rs b/src/agent-client-protocol-test/src/testy.rs
index 55d97d1..570047e 100644
--- a/src/agent-client-protocol-test/src/testy.rs
+++ b/src/agent-client-protocol-test/src/testy.rs
@@ -31,7 +31,7 @@ use agent_client_protocol::schema::v1::{
     CompleteElicitationNotification, CreateElicitationRequest, ElicitationAction,
     ElicitationCapabilities, ElicitationFormMode, ElicitationRequestScope, ElicitationSchema,
     ElicitationSessionScope, ElicitationUrlMode, ErrorCode, MultiSelectPropertySchema, RequestId,
-    StringPropertySchema, UrlElicitationRequiredData, UrlElicitationRequiredItem,
+    StringPropertySchema,
 };
 use agent_client_protocol::{
     Agent, Client, ConnectTo, ConnectionTo, JsonRpcRequest, Responder, SentRequest,
@@ -637,7 +637,7 @@ impl Testy {
             Err(error) => {
                 self.finish_prompt(&session_id, StopReason::EndTurn);
                 #[cfg(feature = "unstable")]
-                if error.code == ErrorCode::UrlElicitationRequired {
+                if is_url_elicitation_required_error(&error) {
                     return responder.respond_with_error(error);
                 }
                 return Err(error);
@@ -1765,15 +1765,28 @@ fn elicitation_cancelled(agent: &Testy, session_id: &SessionId, report: &mut Vec
 
 #[cfg(feature = "unstable")]
 fn url_elicitation_required_error() -> agent_client_protocol::Error {
-    let data = UrlElicitationRequiredData::new(vec![UrlElicitationRequiredItem::new(
-        "testy-url-required",
-        "https://example.com/testy/required",
-        "Complete the Testy URL elicitation before continuing",
-    )]);
-    match serde_json::to_value(data) {
-        Ok(data) => agent_client_protocol::Error::url_elicitation_required().data(data),
-        Err(error) => agent_client_protocol::Error::into_internal_error(error),
-    }
+    agent_client_protocol::Error::invalid_params().data(url_elicitation_required_data())
+}
+
+#[cfg(feature = "unstable")]
+fn is_url_elicitation_required_error(error: &agent_client_protocol::Error) -> bool {
+    error.code == ErrorCode::InvalidParams
+        && error
+            .data
+            .as_ref()
+            .is_some_and(|data| data.get("elicitations").is_some())
+}
+
+#[cfg(feature = "unstable")]
+fn url_elicitation_required_data() -> serde_json::Value {
+    serde_json::json!({
+        "elicitations": [{
+            "mode": "url",
+            "elicitationId": "testy-url-required",
+            "url": "https://example.com/testy/required",
+            "message": "Complete the Testy URL elicitation before continuing"
+        }]
+    })
 }
 
 fn send_session_update(
diff --git a/src/agent-client-protocol-test/tests/testy.rs b/src/agent-client-protocol-test/tests/testy.rs
index cdfc0bf..0c2c7fc 100644
--- a/src/agent-client-protocol-test/tests/testy.rs
+++ b/src/agent-client-protocol-test/tests/testy.rs
@@ -12,7 +12,7 @@ use agent_client_protocol::schema::v1::{
     CompleteElicitationNotification, CreateElicitationRequest, CreateElicitationResponse,
     ElicitationAcceptAction, ElicitationAction, ElicitationCapabilities, ElicitationContentValue,
     ElicitationFormCapabilities, ElicitationMode, ElicitationScope, ElicitationUrlCapabilities,
-    ErrorCode, UrlElicitationRequiredData,
+    ErrorCode,
 };
 use agent_client_protocol::{
     Client, Responder,
@@ -1958,18 +1958,18 @@ async fn testy_callbacks_with_unstable_feature_returns_url_required_when_url_eli
                 .block_task()
                 .await
                 .expect_err("url-required elicitation scenario should fail the prompt request");
-            assert_eq!(error.code, ErrorCode::UrlElicitationRequired);
-
-            let data: UrlElicitationRequiredData =
-                serde_json::from_value(error.data.expect("url-required error should include data"))
-                    .expect("url-required error data should deserialize");
-            assert_eq!(data.elicitations.len(), 1);
-            let elicitation = &data.elicitations[0];
-            assert_eq!(elicitation.elicitation_id.to_string(), "testy-url-required");
-            assert_eq!(elicitation.url, "https://example.com/testy/required");
+            assert_eq!(error.code, ErrorCode::InvalidParams);
+
             assert_eq!(
-                elicitation.message,
-                "Complete the Testy URL elicitation before continuing"
+                error.data.expect("url-required error should include data"),
+                serde_json::json!({
+                    "elicitations": [{
+                        "mode": "url",
+                        "elicitationId": "testy-url-required",
+                        "url": "https://example.com/testy/required",
+                        "message": "Complete the Testy URL elicitation before continuing"
+                    }]
+                })
             );
             Ok(())
         })
diff --git a/src/agent-client-protocol/src/capabilities.rs b/src/agent-client-protocol/src/capabilities.rs
index 21517fa..1718f08 100644
--- a/src/agent-client-protocol/src/capabilities.rs
+++ b/src/agent-client-protocol/src/capabilities.rs
@@ -142,7 +142,7 @@ mod tests {
 
     #[test]
     fn test_add_capability_to_request() {
-        let request = InitializeRequest::new(ProtocolVersion::LATEST);
+        let request = InitializeRequest::new(ProtocolVersion::V1);
 
         let request = request.add_meta_capability(TestCapability);
 
@@ -165,8 +165,8 @@ mod tests {
         );
         let client_capabilities = ClientCapabilities::new().meta(meta);
 
-        let request = InitializeRequest::new(ProtocolVersion::LATEST)
-            .client_capabilities(client_capabilities);
+        let request =
+            InitializeRequest::new(ProtocolVersion::V1).client_capabilities(client_capabilities);
 
         let request = request.remove_meta_capability(TestCapability);
 
@@ -175,7 +175,7 @@ mod tests {
 
     #[test]
     fn test_add_capability_to_response() {
-        let response = InitializeResponse::new(ProtocolVersion::LATEST);
+        let response = InitializeResponse::new(ProtocolVersion::V1);
 
         let response = response.add_meta_capability(TestCapability);
 
@@ -198,8 +198,8 @@ mod tests {
         );
         let client_capabilities = ClientCapabilities::new().meta(meta);
 
-        let request = InitializeRequest::new(ProtocolVersion::LATEST)
-            .client_capabilities(client_capabilities);
+        let request =
+            InitializeRequest::new(ProtocolVersion::V1).client_capabilities(client_capabilities);
 
         assert!(!request.has_meta_capability(TestCapability));
     }
@@ -216,8 +216,8 @@ mod tests {
         );
         let client_capabilities = ClientCapabilities::new().meta(meta);
 
-        let request = InitializeRequest::new(ProtocolVersion::LATEST)
-            .client_capabilities(client_capabilities);
+        let request =
+            InitializeRequest::new(ProtocolVersion::V1).client_capabilities(client_capabilities);
 
         assert!(!request.has_meta_capability(TestCapability));
     }
diff --git a/src/agent-client-protocol/src/jsonrpc/protocol_compat.rs b/src/agent-client-protocol/src/jsonrpc/protocol_compat.rs
index cbca8fe..8626457 100644
--- a/src/agent-client-protocol/src/jsonrpc/protocol_compat.rs
+++ b/src/agent-client-protocol/src/jsonrpc/protocol_compat.rs
@@ -536,7 +536,11 @@ mod imp {
     }
 
     fn public_to_v2_message(message: UntypedMessage) -> Result<UntypedMessage, crate::Error> {
-        let UntypedMessage { method, params } = message;
+        let UntypedMessage { method, mut params } = message;
+
+        if method == "initialize" {
+            ensure_legacy_initialize_info(&mut params, "clientInfo");
+        }
 
         if let Some(message) = try_convert_message_to_v2::<ClientRequest>(&method, &params)? {
             return Ok(message);
@@ -573,8 +577,12 @@ mod imp {
 
     fn public_to_v2_response(
         method: &str,
-        value: serde_json::Value,
+        mut value: serde_json::Value,
     ) -> Result<serde_json::Value, crate::Error> {
+        if method == "initialize" {
+            ensure_legacy_initialize_info(&mut value, "agentInfo");
+        }
+
         if let Some(value) = try_convert_response_to_v2::<AgentResponse>(method, &value)? {
             return Ok(value);
         }
@@ -585,6 +593,27 @@ mod imp {
         Ok(value)
     }
 
+    fn ensure_legacy_initialize_info(value: &mut serde_json::Value, field: &str) {
+        let serde_json::Value::Object(object) = value else {
+            return;
+        };
+
+        let needs_default = match object.get(field) {
+            Some(value) => value.is_null(),
+            None => true,
+        };
+
+        if needs_default {
+            object.insert(
+                field.into(),
+                serde_json::json!({
+                    "name": "legacy-acp-peer",
+                    "version": "unknown",
+                }),
+            );
+        }
+    }
+
     fn v2_to_public_response(
         method: &str,
         value: serde_json::Value,
@@ -728,6 +757,10 @@ mod imp {
                 .negotiated
         }
 
+        fn v2_implementation() -> v2::Implementation {
+            v2::Implementation::new("rust-sdk-test", "0.0.0")
+        }
+
         #[test]
         fn initialize_request_sets_active_wire_version_before_response() -> Result<(), crate::Error>
         {
@@ -736,7 +769,7 @@ mod imp {
 
             compat.incoming_message(UntypedMessage::new(
                 "initialize",
-                v2::InitializeRequest::new(ProtocolVersion::V2),
+                v2::InitializeRequest::new(ProtocolVersion::V2, v2_implementation()),
             )?)?;
 
             assert_eq!(negotiated(&compat), ProtocolVersionKind::V1);
@@ -746,6 +779,7 @@ mod imp {
                 "initialize",
                 Ok(serde_json::to_value(v2::InitializeResponse::new(
                     ProtocolVersion::V2,
+                    v2_implementation(),
                 ))?),
             )?;
 
@@ -762,7 +796,7 @@ mod imp {
 
             compat.outgoing_message(UntypedMessage::new(
                 "initialize",
-                v2::InitializeRequest::new(ProtocolVersion::V1),
+                v2::InitializeRequest::new(ProtocolVersion::V1, v2_implementation()),
             )?)?;
 
             assert_eq!(negotiated(&compat), ProtocolVersionKind::V1);
@@ -772,6 +806,7 @@ mod imp {
                 "initialize",
                 Ok(serde_json::to_value(v2::InitializeResponse::new(
                     ProtocolVersion::V2,
+                    v2_implementation(),
                 ))?),
             )?;
 
@@ -788,7 +823,7 @@ mod imp {
 
             compat.outgoing_message(UntypedMessage::new(
                 "initialize",
-                v2::InitializeRequest::new(ProtocolVersion::V1),
+                v2::InitializeRequest::new(ProtocolVersion::V1, v2_implementation()),
             )?)?;
 
             assert_eq!(negotiated(&compat), ProtocolVersionKind::V1);
@@ -814,7 +849,7 @@ mod imp {
                 let compat = ProtocolCompat::new(ProtocolMode::v2_client());
                 compat.outgoing_message(UntypedMessage::new(
                     "initialize",
-                    v2::InitializeRequest::new(ProtocolVersion::V1),
+                    v2::InitializeRequest::new(ProtocolVersion::V1, v2_implementation()),
                 )?)?;
 
                 let error = compat
@@ -838,7 +873,7 @@ mod imp {
             let compat = ProtocolCompat::new(ProtocolMode::v2_agent());
             let messages = compat.outgoing_notification(UntypedMessage::new(
                 "session/update",
-                v2::SessionNotification::new(
+                v2::UpdateSessionNotification::new(
                     "sess",
                     v2::SessionUpdate::AgentMessage(v2::AgentMessage::new("msg_agent").content(
                         vec![
diff --git a/src/agent-client-protocol/src/schema/client_to_agent/requests.rs b/src/agent-client-protocol/src/schema/client_to_agent/requests.rs
index 7a4f233..d7bb5eb 100644
--- a/src/agent-client-protocol/src/schema/client_to_agent/requests.rs
+++ b/src/agent-client-protocol/src/schema/client_to_agent/requests.rs
@@ -5,6 +5,7 @@ use crate::schema::v1::{
     LogoutRequest, LogoutResponse, NewSessionRequest, NewSessionResponse, PromptRequest,
     PromptResponse, ResumeSessionRequest, ResumeSessionResponse, SetSessionConfigOptionRequest,
     SetSessionConfigOptionResponse, SetSessionModeRequest, SetSessionModeResponse,
+    SetSessionTitleRequest, SetSessionTitleResponse,
 };
 #[cfg(feature = "unstable_session_fork")]
 use crate::schema::v1::{ForkSessionRequest, ForkSessionResponse};
@@ -31,6 +32,11 @@ impl_jsonrpc_request!(
     SetSessionConfigOptionResponse,
     "session/set_config_option"
 );
+impl_jsonrpc_request!(
+    SetSessionTitleRequest,
+    SetSessionTitleResponse,
+    "session/setTitle"
+);
 
 #[cfg(feature = "unstable_session_fork")]
 impl_jsonrpc_request!(ForkSessionRequest, ForkSessionResponse, "session/fork");
diff --git a/src/agent-client-protocol/src/schema/enum_impls.rs b/src/agent-client-protocol/src/schema/enum_impls.rs
index 680158b..b730ddc 100644
--- a/src/agent-client-protocol/src/schema/enum_impls.rs
+++ b/src/agent-client-protocol/src/schema/enum_impls.rs
@@ -24,6 +24,7 @@ impl_jsonrpc_request_enum!(ClientRequest {
     CloseSessionRequest => "session/close",
     SetSessionModeRequest => "session/set_mode",
     SetSessionConfigOptionRequest => "session/set_config_option",
+    SetSessionTitleRequest => "session/setTitle",
     PromptRequest => "session/prompt",
     #[cfg(feature = "unstable_mcp_over_acp")]
     MessageMcpRequest => "mcp/message",
diff --git a/src/agent-client-protocol/src/schema/v2_impls.rs b/src/agent-client-protocol/src/schema/v2_impls.rs
index d87ad71..73883bd 100644
--- a/src/agent-client-protocol/src/schema/v2_impls.rs
+++ b/src/agent-client-protocol/src/schema/v2_impls.rs
@@ -107,10 +107,10 @@ macro_rules! impl_v2_jsonrpc_request_enum {
                         if method.starts_with('_') {
                             crate::util::json_cast_params(params).map(
                                 |ext_req: v2::ExtRequest| {
-                                    Self::$ext_variant(v2::ExtRequest::new(
+                                    Self::$ext_variant(Box::new(v2::ExtRequest::new(
                                         method.to_string(),
                                         ext_req.params,
-                                    ))
+                                    )))
                                 },
                             )
                         } else {
@@ -159,10 +159,10 @@ macro_rules! impl_v2_jsonrpc_notification_enum {
                         if method.starts_with('_') {
                             crate::util::json_cast_params(params).map(
                                 |ext_notif: v2::ExtNotification| {
-                                    Self::$ext_variant(v2::ExtNotification::new(
+                                    Self::$ext_variant(Box::new(v2::ExtNotification::new(
                                         method.to_string(),
                                         ext_notif.params,
-                                    ))
+                                    )))
                                 },
                             )
                         } else {
@@ -210,12 +210,8 @@ macro_rules! impl_v2_jsonrpc_response_enum {
 }
 
 impl_v2_jsonrpc_request!(v2::InitializeRequest, v2::InitializeResponse, "initialize");
-impl_v2_jsonrpc_request!(
-    v2::AuthenticateRequest,
-    v2::AuthenticateResponse,
-    "authenticate"
-);
-impl_v2_jsonrpc_request!(v2::LogoutRequest, v2::LogoutResponse, "logout");
+impl_v2_jsonrpc_request!(v2::LoginAuthRequest, v2::LoginAuthResponse, "auth/login");
+impl_v2_jsonrpc_request!(v2::LogoutAuthRequest, v2::LogoutAuthResponse, "auth/logout");
 impl_v2_jsonrpc_request!(v2::NewSessionRequest, v2::NewSessionResponse, "session/new");
 impl_v2_jsonrpc_request!(
     v2::LoadSessionRequest,
@@ -248,6 +244,11 @@ impl_v2_jsonrpc_request!(
     v2::CloseSessionResponse,
     "session/close"
 );
+impl_v2_jsonrpc_request!(
+    v2::SetSessionTitleRequest,
+    v2::SetSessionTitleResponse,
+    "session/setTitle"
+);
 impl_v2_jsonrpc_request!(
     v2::SetSessionConfigOptionRequest,
     v2::SetSessionConfigOptionResponse,
@@ -259,7 +260,7 @@ impl_v2_jsonrpc_request!(v2::MessageMcpRequest, v2::MessageMcpResponse, "mcp/mes
 
 #[cfg(feature = "unstable_cancel_request")]
 impl_v2_jsonrpc_notification!(v2::CancelRequestNotification, "$/cancel_request");
-impl_v2_jsonrpc_notification!(v2::CancelNotification, "session/cancel");
+impl_v2_jsonrpc_notification!(v2::CancelSessionNotification, "session/cancel");
 #[cfg(feature = "unstable_mcp_over_acp")]
 impl_v2_jsonrpc_notification!(v2::MessageMcpNotification, "mcp/message");
 
@@ -283,7 +284,7 @@ impl_v2_jsonrpc_request!(
     "mcp/disconnect"
 );
 
-impl_v2_jsonrpc_notification!(v2::SessionNotification, "session/update");
+impl_v2_jsonrpc_notification!(v2::UpdateSessionNotification, "session/update");
 #[cfg(feature = "unstable_elicitation")]
 impl_v2_jsonrpc_notification!(v2::CompleteElicitationNotification, "elicitation/complete");
 
@@ -294,8 +295,8 @@ impl_jsonrpc_protocol_level_notification_enum!(v2::ProtocolLevelNotification {
 
 impl_v2_jsonrpc_request_enum!(v2::ClientRequest {
     InitializeRequest => "initialize",
-    AuthenticateRequest => "authenticate",
-    LogoutRequest => "logout",
+    LoginAuthRequest => "auth/login",
+    LogoutAuthRequest => "auth/logout",
     NewSessionRequest => "session/new",
     LoadSessionRequest => "session/load",
     ListSessionsRequest => "session/list",
@@ -304,6 +305,7 @@ impl_v2_jsonrpc_request_enum!(v2::ClientRequest {
     ForkSessionRequest => "session/fork",
     ResumeSessionRequest => "session/resume",
     CloseSessionRequest => "session/close",
+    SetSessionTitleRequest => "session/setTitle",
     SetSessionConfigOptionRequest => "session/set_config_option",
     PromptRequest => "session/prompt",
     #[cfg(feature = "unstable_mcp_over_acp")]
@@ -313,8 +315,8 @@ impl_v2_jsonrpc_request_enum!(v2::ClientRequest {
 
 impl_v2_jsonrpc_response_enum!(v2::AgentResponse {
     InitializeResponse => "initialize",
-    AuthenticateResponse => "authenticate",
-    LogoutResponse => "logout",
+    LoginAuthResponse => "auth/login",
+    LogoutAuthResponse => "auth/logout",
     NewSessionResponse => "session/new",
     LoadSessionResponse => "session/load",
     ListSessionsResponse => "session/list",
@@ -323,6 +325,7 @@ impl_v2_jsonrpc_response_enum!(v2::AgentResponse {
     ForkSessionResponse => "session/fork",
     ResumeSessionResponse => "session/resume",
     CloseSessionResponse => "session/close",
+    SetSessionTitleResponse => "session/setTitle",
     SetSessionConfigOptionResponse => "session/set_config_option",
     PromptResponse => "session/prompt",
     #[cfg(feature = "unstable_mcp_over_acp")]
@@ -331,7 +334,7 @@ impl_v2_jsonrpc_response_enum!(v2::AgentResponse {
 });
 
 impl_v2_jsonrpc_notification_enum!(v2::ClientNotification {
-    CancelNotification => "session/cancel",
+    CancelSessionNotification => "session/cancel",
     #[cfg(feature = "unstable_mcp_over_acp")]
     MessageMcpNotification => "mcp/message",
     [ext] ExtNotification,
@@ -364,7 +367,7 @@ impl_v2_jsonrpc_response_enum!(v2::ClientResponse {
 });
 
 impl_v2_jsonrpc_notification_enum!(v2::AgentNotification {
-    SessionNotification => "session/update",
+    UpdateSessionNotification => "session/update",
     #[cfg(feature = "unstable_elicitation")]
     CompleteElicitationNotification => "elicitation/complete",
     #[cfg(feature = "unstable_mcp_over_acp")]
diff --git a/src/agent-client-protocol/tests/protocol_v2.rs b/src/agent-client-protocol/tests/protocol_v2.rs
index f05f032..994d02e 100644
--- a/src/agent-client-protocol/tests/protocol_v2.rs
+++ b/src/agent-client-protocol/tests/protocol_v2.rs
@@ -49,10 +49,14 @@ fn cwd() -> Result<PathBuf, Error> {
     std::env::current_dir().map_err(Error::into_internal_error)
 }
 
+fn v2_implementation() -> v2::Implementation {
+    v2::Implementation::new("rust-sdk-test", "0.0.0")
+}
+
 fn v2_initialize_response_with_session(
     protocol_version: ProtocolVersion,
 ) -> v2::InitializeResponse {
-    v2::InitializeResponse::new(protocol_version)
+    v2::InitializeResponse::new(protocol_version, v2_implementation())
         .capabilities(v2::AgentCapabilities::new().session(v2::SessionCapabilities::new()))
 }
 
@@ -110,7 +114,10 @@ async fn assert_v2_client_rejected_by_v1_agent(agent: impl ConnectTo<Client>) ->
         .v2()
         .connect_with(agent, async |cx| {
             let error = cx
-                .send_request(v2::InitializeRequest::new(ProtocolVersion::V2))
+                .send_request(v2::InitializeRequest::new(
+                    ProtocolVersion::V2,
+                    v2_implementation(),
+                ))
                 .block_task()
                 .await
                 .expect_err("v1 agent protocol mode should reject v2 clients");
@@ -173,7 +180,10 @@ async fn role_builder_v1_agent_rejects_v2_client_negotiation() -> Result<(), Err
         .v2()
         .connect_with(agent, async |cx| {
             let error = cx
-                .send_request(v2::InitializeRequest::new(ProtocolVersion::V2))
+                .send_request(v2::InitializeRequest::new(
+                    ProtocolVersion::V2,
+                    v2_implementation(),
+                ))
                 .block_task()
                 .await
                 .expect_err("Role::builder should preserve v1 agent protocol mode");
@@ -499,7 +509,10 @@ async fn v2_client_rejects_v1_agent() -> Result<(), Error> {
         .v2()
         .connect_with(Testy::new(), async |cx| {
             let error = cx
-                .send_request(v2::InitializeRequest::new(ProtocolVersion::V1))
+                .send_request(v2::InitializeRequest::new(
+                    ProtocolVersion::V1,
+                    v2_implementation(),
+                ))
                 .block_task()
                 .await
                 .expect_err("v2 clients require a v2 agent");
@@ -524,7 +537,9 @@ async fn v2_client_and_agent_negotiate_v2() -> Result<(), Error> {
         .on_receive_request(
             async |initialize: v2::InitializeRequest, responder, _cx| {
                 assert_eq!(initialize.protocol_version, ProtocolVersion::V2);
-                responder.respond(v2::InitializeResponse::new(initialize.protocol_version))
+                responder.respond(v2_initialize_response_with_session(
+                    initialize.protocol_version,
+                ))
             },
             agent_client_protocol::on_receive_request!(),
         )
@@ -542,7 +557,10 @@ async fn v2_client_and_agent_negotiate_v2() -> Result<(), Error> {
         .v2()
         .connect_with(agent, async |cx| {
             let initialize = cx
-                .send_request(v2::InitializeRequest::new(ProtocolVersion::V1))
+                .send_request(v2::InitializeRequest::new(
+                    ProtocolVersion::V1,
+                    v2_implementation(),
+                ))
                 .block_task()
                 .await?;
             assert_eq!(initialize.protocol_version, ProtocolVersion::V2);
@@ -596,7 +614,10 @@ async fn v2_client_can_cancel_request_to_v2_agent() -> Result<(), Error> {
         .v2()
         .connect_with(v2_agent_with_cancellable_new_session(), async |cx| {
             let initialize = cx
-                .send_request(v2::InitializeRequest::new(ProtocolVersion::V2))
+                .send_request(v2::InitializeRequest::new(
+                    ProtocolVersion::V2,
+                    v2_implementation(),
+                ))
                 .block_task()
                 .await?;
             assert_eq!(initialize.protocol_version, ProtocolVersion::V2);
diff --git a/src/agent-client-protocol/tests/schema_elicitation.rs b/src/agent-client-protocol/tests/schema_elicitation.rs
index 8ea8dc9..c6ec56d 100644
--- a/src/agent-client-protocol/tests/schema_elicitation.rs
+++ b/src/agent-client-protocol/tests/schema_elicitation.rs
@@ -4,8 +4,7 @@ use agent_client_protocol::schema::v1::{
     AgentNotification, AgentRequest, ClientCapabilities, ClientResponse,
     CompleteElicitationNotification, CreateElicitationRequest, CreateElicitationResponse,
     ElicitationAction, ElicitationCapabilities, ElicitationFormCapabilities, ElicitationFormMode,
-    ElicitationSchema, ElicitationSessionScope, ElicitationUrlCapabilities, Error, ErrorCode,
-    UrlElicitationRequiredData, UrlElicitationRequiredItem,
+    ElicitationSchema, ElicitationSessionScope, ElicitationUrlCapabilities, Error,
 };
 use agent_client_protocol::{JsonRpcMessage, JsonRpcNotification, JsonRpcRequest, JsonRpcResponse};
 use serde::Serialize;
@@ -123,29 +122,6 @@ fn client_capabilities_can_declare_elicitation_modes() {
     assert!(parsed.elicitation.is_some());
 }
 
-#[test]
-fn url_elicitation_required_error_helper_is_available() {
-    let data = UrlElicitationRequiredData::new(vec![UrlElicitationRequiredItem::new(
-        "elicit_1",
-        "https://example.com/connect",
-        "Connect your account",
-    )]);
-    let error = Error::url_elicitation_required().data(json_value(data).unwrap());
-
-    assert_eq!(error.code, ErrorCode::UrlElicitationRequired);
-    assert_eq!(
-        error.data.unwrap(),
-        json!({
-            "elicitations": [{
-                "mode": "url",
-                "elicitationId": "elicit_1",
-                "url": "https://example.com/connect",
-                "message": "Connect your account"
-            }]
-        })
-    );
-}
-
 #[cfg(feature = "unstable_protocol_v2")]
 #[test]
 fn protocol_v2_elicitation_variants_are_jsonrpc_mapped() -> Result<(), Error> {
@@ -191,10 +167,14 @@ async fn v2_agent_can_elicit_from_v1_client_before_prompt_completion() -> Result
     use agent_client_protocol::{Agent, Client};
     use std::collections::BTreeMap;
 
+    fn v2_implementation() -> v2::Implementation {
+        v2::Implementation::new("rust-sdk-test", "0.0.0")
+    }
+
     fn v2_initialize_response_with_session(
         protocol_version: ProtocolVersion,
     ) -> v2::InitializeResponse {
-        v2::InitializeResponse::new(protocol_version)
+        v2::InitializeResponse::new(protocol_version, v2_implementation())
             .capabilities(v2::AgentCapabilities::new().session(v2::SessionCapabilities::new()))
     }