diff --git a/cmd/archive.go b/cmd/archive.go
index 08a4b98..9915c71 100644
--- a/cmd/archive.go
+++ b/cmd/archive.go
@@ -11,10 +11,11 @@ import (
 )
 
 var archiveCmd = &cobra.Command{
-	Use:   "archive <query>",
-	Short: "Mark a workspace as archived",
-	Args:  cobra.ExactArgs(1),
-	RunE:  runArchive,
+	Use:          "archive <query>",
+	Short:        "Mark a workspace as archived",
+	Args:         cobra.ExactArgs(1),
+	SilenceUsage: true,
+	RunE:         runArchive,
 }
 
 func init() {
diff --git a/cmd/info.go b/cmd/info.go
index 014a476..8fb7838 100644
--- a/cmd/info.go
+++ b/cmd/info.go
@@ -11,8 +11,9 @@ import (
 var infoCmd = &cobra.Command{
 	Use:   "info <query>",
 	Short: "Display metadata and path for a workspace",
-	Args:  cobra.ExactArgs(1),
-	RunE:  runInfo,
+	Args:         cobra.ExactArgs(1),
+	SilenceUsage: true,
+	RunE:         runInfo,
 }
 
 var infoAll bool
diff --git a/cmd/list.go b/cmd/list.go
index 313db2c..4c38a96 100644
--- a/cmd/list.go
+++ b/cmd/list.go
@@ -14,8 +14,9 @@ import (
 var listCmd = &cobra.Command{
 	Use:   "list",
 	Short: "Show recent workspaces in reverse-chronological order",
-	Args:  cobra.NoArgs,
-	RunE:  runList,
+	Args:         cobra.NoArgs,
+	SilenceUsage: true,
+	RunE:         runList,
 }
 
 var (
diff --git a/cmd/new.go b/cmd/new.go
index 58d7114..a91e32c 100644
--- a/cmd/new.go
+++ b/cmd/new.go
@@ -13,8 +13,9 @@ var newCmd = &cobra.Command{
 	Use:   "new [title]",
 	Short: "Create a new task workspace and launch the agent",
 	Long:  "Create a new task workspace and launch the agent. If title is omitted, generates task-HHMMSS.",
-	Args:  cobra.MaximumNArgs(1),
-	RunE:  runNew,
+	Args:         cobra.MaximumNArgs(1),
+	SilenceUsage: true,
+	RunE:         runNew,
 }
 
 var (
diff --git a/cmd/open.go b/cmd/open.go
index cadcd5c..4afc3b6 100644
--- a/cmd/open.go
+++ b/cmd/open.go
@@ -12,10 +12,11 @@ import (
 )
 
 var openCmd = &cobra.Command{
-	Use:   "open <query>",
-	Short: "Open a workspace directory without launching the agent",
-	Args:  cobra.ExactArgs(1),
-	RunE:  runOpen,
+	Use:          "open <query>",
+	Short:        "Open a workspace directory without launching the agent",
+	Args:         cobra.ExactArgs(1),
+	SilenceUsage: true,
+	RunE:         runOpen,
 }
 
 var openAll bool
diff --git a/cmd/resume.go b/cmd/resume.go
index eaaf571..3603f90 100644
--- a/cmd/resume.go
+++ b/cmd/resume.go
@@ -12,10 +12,11 @@ import (
 )
 
 var resumeCmd = &cobra.Command{
-	Use:   "resume <query>",
-	Short: "Reopen an existing workspace and launch the agent",
-	Args:  cobra.ExactArgs(1),
-	RunE:  runResume,
+	Use:          "resume <query>",
+	Short:        "Reopen an existing workspace and launch the agent",
+	Args:         cobra.ExactArgs(1),
+	SilenceUsage: true,
+	RunE:         runResume,
 }
 
 var (
diff --git a/main.go b/main.go
index ba5c36f..61bad87 100644
--- a/main.go
+++ b/main.go
@@ -2,12 +2,23 @@ package main
 
 import (
 	"os"
+	"strings"
 
 	"github.com/warrenronsiek/ctask/cmd"
 )
 
 func main() {
 	if err := cmd.Execute(); err != nil {
+		msg := err.Error()
+		// Exit code 127 for agent command not found (per spec)
+		if strings.Contains(msg, "agent command not found") {
+			os.Exit(127)
+		}
+		// Exit code 2 for missing required arguments (per spec)
+		if strings.Contains(msg, "accepts") && strings.Contains(msg, "received 0") {
+			os.Exit(2)
+		}
 		os.Exit(1)
 	}
 }
+