diff --git a/packages/pi-agent-core/src/agent.ts b/packages/pi-agent-core/src/agent.ts
index c6b998b6a..519311c54 100644
--- a/packages/pi-agent-core/src/agent.ts
+++ b/packages/pi-agent-core/src/agent.ts
@@ -438,7 +438,7 @@ export class Agent {
 	) {
 		if (this._state.isStreaming) {
 			throw new Error(
-				"Agent is already processing a prompt. Use steer() or followUp() to queue messages, or wait for completion.",
+				"Agent is already processing a prompt. Please wait for it to finish before sending another message.",
 			);
 		}
 
diff --git a/packages/pi-coding-agent/src/core/agent-session-custom-message-queue.test.ts b/packages/pi-coding-agent/src/core/agent-session-custom-message-queue.test.ts
index 77a7e2ccc..cac943f51 100644
--- a/packages/pi-coding-agent/src/core/agent-session-custom-message-queue.test.ts
+++ b/packages/pi-coding-agent/src/core/agent-session-custom-message-queue.test.ts
@@ -59,7 +59,7 @@ describe("AgentSession custom message queueing", () => {
 		const steered: AgentMessage[] = [];
 		agent.prompt = async () => {
 			throw new Error(
-				"Agent is already processing a prompt. Use steer() or followUp() to queue messages, or wait for completion.",
+				"Agent is already processing a prompt. Please wait for it to finish before sending another message.",
 			);
 		};
 		agent.steer = (message) => {
@@ -89,7 +89,7 @@ describe("AgentSession custom message queueing", () => {
 		const followUps: AgentMessage[] = [];
 		agent.prompt = async () => {
 			throw new Error(
-				"Agent is already processing a prompt. Use steer() or followUp() to queue messages, or wait for completion.",
+				"Agent is already processing a prompt. Please wait for it to finish before sending another message.",
 			);
 		};
 		agent.followUp = (message) => {
diff --git a/packages/pi-coding-agent/src/core/agent-session.ts b/packages/pi-coding-agent/src/core/agent-session.ts
index 63300ca9c..6e0910971 100644
--- a/packages/pi-coding-agent/src/core/agent-session.ts
+++ b/packages/pi-coding-agent/src/core/agent-session.ts
@@ -1218,7 +1218,7 @@ export class AgentSession {
 		if (this.isStreaming) {
 			if (!options?.streamingBehavior) {
 				throw new Error(
-					"Agent is already processing. Specify streamingBehavior ('steer' or 'followUp') to queue the message.",
+					"Agent is already processing. Please wait for it to finish before sending another message.",
 				);
 			}
 			if (options.streamingBehavior === "followUp") {