diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 98fffdc..bc4e2ff 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -276,8 +276,8 @@ jobs:
 
         # Test help shows new commands
         echo "Testing: help shows stop/start commands"
-        $BINARY_PATH --help | grep -q "stop" && echo "✅ stop command documented" || echo "❌ stop command missing"
-        $BINARY_PATH --help | grep -q "start" && echo "✅ start command documented" || echo "❌ start command missing"
+        $BINARY_PATH breeder --help | grep -q "stop" && echo "✅ stop command documented" || echo "❌ stop command missing"
+        $BINARY_PATH breeder --help | grep -q "start" && echo "✅ start command documented" || echo "❌ start command missing"
         echo "Testing: breeder purge --help shows --force flag"
         $BINARY_PATH breeder purge --help | grep -q "force" && echo "✅ --force flag documented in purge" || echo "❌ --force flag missing from purge"
 
@@ -321,6 +321,54 @@ jobs:
         $BINARY_PATH --hostname=localhost --port=4010 --debug breeder list
         echo "✅ --debug flag works"
 
+        # === Error Handling Tests ===
+        echo ""
+        echo "=== Testing Error Handling ==="
+
+        # Test missing file
+        echo "Testing: missing file error"
+        if $BINARY_PATH --hostname=localhost --port=4010 breeder create --name=test --file=nonexistent.yml 2>/dev/null; then
+          echo "❌ Should have failed on missing file"
+          exit 1
+        else
+          echo "✅ Failed on missing file as expected"
+        fi
+
+        # Test missing required argument
+        echo "Testing: missing --id argument"
+        if $BINARY_PATH --hostname=localhost --port=4010 breeder show 2>/dev/null; then
+          echo "❌ Should have failed on missing --id"
+          exit 1
+        else
+          echo "✅ Failed on missing --id as expected"
+        fi
+
+        # === Output Format Tests ===
+        echo ""
+        echo "=== Testing Output Formats ==="
+
+        echo "Testing: JSON output format"
+        JSON_OUTPUT=$($BINARY_PATH --hostname=localhost --port=4010 --output=json breeder list)
+        if echo "$JSON_OUTPUT" | grep -q '"id"\|"name"\|"status"'; then
+          echo "✅ JSON output contains expected fields"
+        else
+          echo "❌ JSON output missing expected fields"
+        fi
+
+        echo "Testing: YAML output format"
+        YAML_OUTPUT=$($BINARY_PATH --hostname=localhost --port=4010 --output=yaml breeder list)
+        if echo "$YAML_OUTPUT" | grep -q -e '^-' -e 'id:' -e 'name:'; then
+          echo "✅ YAML output contains expected fields"
+        else
+          echo "❌ YAML output missing expected fields"
+        fi
+
+        echo "Testing: JSON output for breeder show"
+        $BINARY_PATH --hostname=localhost --port=4010 --output=json breeder show --id=550e8400-e29b-41d4-a716-446655440000
+
+        echo "Testing: YAML output for credential list"
+        $BINARY_PATH --hostname=localhost --port=4010 --output=yaml credential list
+
     - name: Cleanup Prism container
       if: always()
       run: |
diff --git a/README.md b/README.md
index 6cd137c..c592bcd 100644
--- a/README.md
+++ b/README.md
@@ -1,6 +1,6 @@
 # Godon CLI
 
-A Nim-based CLI tool for controlling and managing the Godon optimizer breeders via the Godon Control API.
+A Rust-based CLI tool for controlling and managing the Godon optimizer breeders via the Godon Control API.
 
 ## Features
 
@@ -146,7 +146,7 @@ Create a YAML configuration file `credential.yaml`:
 
 ```yaml
 name: "production_ssh_key"
-credential_type: "ssh_private_key"
+credentialType: "ssh_private_key"
 description: "SSH key for production servers"
 content: |
   -----BEGIN RSA PRIVATE KEY-----
diff --git a/src/main.rs b/src/main.rs
index 27fbbeb..0ac82bf 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -266,13 +266,17 @@ async fn handle_breeder_command(client: &GodonClient, cmd: BreederCommands, outp
 
             let response = client.update_breeder_from_yaml(&content).await;
             if response.success {
-                if matches!(output, OutputFormat::Text) {
-                    if let Some(ref data) = response.data {
-                        let id = data.get("id").and_then(|v| v.as_str()).unwrap_or("unknown");
-                        println!("Breeder updated successfully: {}", id);
+                if let Some(data) = response.data {
+                    match data.get("id").and_then(|v| v.as_str()) {
+                        Some(id) => {
+                            if matches!(output, OutputFormat::Text) {
+                                println!("Breeder updated successfully: {}", id);
+                            } else {
+                                format_output(&data, output);
+                            }
+                        }
+                        None => write_error("Unexpected response format: missing 'id' field"),
                     }
-                } else if let Some(data) = response.data {
-                    format_output(&data, output);
                 }
             } else {
                 write_error(response.error.as_deref().unwrap_or("Unknown error"));