diff --git a/internal/config/errors.go b/internal/config/errors.go
new file mode 100644
index 0000000..ef413e8
--- /dev/null
+++ b/internal/config/errors.go
@@ -0,0 +1,27 @@
+package config
+
+import "git.xdrm.io/go/aicra/internal/cerr"
+
+// ErrRead - a problem ocurred when trying to read the configuration file
+const ErrRead = cerr.Error("cannot read config")
+
+// ErrFormat - a invalid format has been detected
+const ErrFormat = cerr.Error("invalid config format")
+
+// ErrIllegalServiceName - an illegal character has been found in a service name
+const ErrIllegalServiceName = cerr.Error("service must not contain any slash '/' nor '-' symbols")
+
+// ErrMissingMethodDesc - a method is missing its description
+const ErrMissingMethodDesc = cerr.Error("missing method description")
+
+// ErrMissingParamDesc - a parameter is missing its description
+const ErrMissingParamDesc = cerr.Error("missing parameter description")
+
+// ErrIllegalParamName - a parameter has an illegal name
+const ErrIllegalParamName = cerr.Error("illegal parameter name (must not begin/end with '_')")
+
+// ErrMissingParamType - a parameter has an illegal type
+const ErrMissingParamType = cerr.Error("missing parameter type")
+
+// ErrParamNameConflict - a parameter has a conflict with its name/rename field
+const ErrParamNameConflict = cerr.Error("name conflict for parameter")
diff --git a/internal/config/method.go b/internal/config/method.go
index f570b84..1cb2a02 100644
--- a/internal/config/method.go
+++ b/internal/config/method.go
@@ -1,7 +1,6 @@
 package config
 
 import (
-	"fmt"
 	"strings"
 )
 
@@ -10,7 +9,7 @@ func (methodDef *Method) checkAndFormat(servicePath string, httpMethod string) e
 
 	// 1. fail on missing description
 	if len(methodDef.Description) < 1 {
-		return fmt.Errorf("missing %s.%s description", servicePath, httpMethod)
+		return ErrMissingMethodDesc.WrapString(httpMethod + " " + servicePath)
 	}
 
 	// 2. stop if no parameter
@@ -22,16 +21,16 @@ func (methodDef *Method) checkAndFormat(servicePath string, httpMethod string) e
 	// 3. for each parameter
 	for pName, pData := range methodDef.Parameters {
 
-		// check name
+		// 3.1. check name
 		if strings.Trim(pName, "_") != pName {
-			return fmt.Errorf("invalid name '%s' must not begin/end with '_'", pName)
+			return ErrIllegalParamName.WrapString(httpMethod + " " + servicePath + " {" + pName + "}")
 		}
 
 		if len(pData.Rename) < 1 {
 			pData.Rename = pName
 		}
 
-		// 5. Check for name/rename conflict
+		// 3.2. Check for name/rename conflict
 		for paramName, param := range methodDef.Parameters {
 
 			// ignore self
@@ -39,39 +38,34 @@ func (methodDef *Method) checkAndFormat(servicePath string, httpMethod string) e
 				continue
 			}
 
-			// 1. Same rename field
+			// 3.2.1. Same rename field
 			if pData.Rename == param.Rename {
-				return fmt.Errorf("rename conflict for %s.%s parameter '%s'", servicePath, httpMethod, pData.Rename)
+				return ErrParamNameConflict.WrapString(httpMethod + " " + servicePath + " {" + pData.Rename + "}")
 			}
 
-			// 2. Not-renamed field matches a renamed field
+			// 3.2.2. Not-renamed field matches a renamed field
 			if pName == param.Rename {
-				return fmt.Errorf("name conflict for %s.%s parameter '%s'", servicePath, httpMethod, pName)
+				return ErrParamNameConflict.WrapString(httpMethod + " " + servicePath + " {" + pName + "}")
 			}
 
-			// 3. Renamed field matches name
+			// 3.2.3. Renamed field matches name
 			if pData.Rename == paramName {
-				return fmt.Errorf("name conflict for %s.%s parameter '%s'", servicePath, httpMethod, pName)
+				return ErrParamNameConflict.WrapString(httpMethod + " " + servicePath + " {" + pName + "}")
 			}
 
 		}
 
-		// 6. Manage invalid type
-		if len(pData.Type) < 1 {
-			return fmt.Errorf("invalid type for %s.%s parameter '%s'", servicePath, httpMethod, pName)
-		}
-
-		// 7. Fail on missing description
+		// 3.3. Fail on missing description
 		if len(pData.Description) < 1 {
-			return fmt.Errorf("missing description for %s.%s parameter '%s'", servicePath, httpMethod, pName)
+			return ErrMissingParamDesc.WrapString(httpMethod + " " + servicePath + " {" + pName + "}")
 		}
 
-		// 8. Fail on missing type
+		// 3.4. Manage invalid type
 		if len(pData.Type) < 1 {
-			return fmt.Errorf("missing type for %s.%s parameter '%s'", servicePath, httpMethod, pName)
+			return ErrMissingParamType.WrapString(httpMethod + " " + servicePath + " {" + pName + "}")
 		}
 
-		// 9. Set optional + type
+		// 3.5. Set optional + type
 		if pData.Type[0] == '?' {
 			pData.Optional = true
 			pData.Type = pData.Type[1:]
diff --git a/internal/config/service.go b/internal/config/service.go
index cf223fe..1c97701 100644
--- a/internal/config/service.go
+++ b/internal/config/service.go
@@ -2,20 +2,11 @@ package config
 
 import (
 	"encoding/json"
-	"fmt"
 	"io"
 	"net/http"
 	"strings"
-
-	"git.xdrm.io/go/aicra/internal/cerr"
 )
 
-// ErrRead - a problem ocurred when trying to read the configuration file
-const ErrRead = cerr.Error("cannot read config")
-
-// ErrFormat - a invalid format has been detected
-const ErrFormat = cerr.Error("invalid config format")
-
 // Parse builds a service from a json reader and checks for most format errors.
 func Parse(r io.Reader) (*Service, error) {
 	receiver := &Service{}
@@ -87,20 +78,20 @@ func (svc *Service) checkAndFormat(servicePath string) error {
 		}
 	}
 
-	// 1. stop if no child */
+	// 2. stop if no child */
 	if svc.Children == nil || len(svc.Children) < 1 {
 		return nil
 	}
 
-	// 2. for each service */
+	// 3. for each service */
 	for childService, ctl := range svc.Children {
 
-		// 3. invalid name */
+		// 3.1. invalid name */
 		if strings.ContainsAny(childService, "/-") {
-			return fmt.Errorf("service '%s' must not contain any slash '/' nor '-' symbols", childService)
+			return ErrIllegalServiceName.WrapString(childService)
 		}
 
-		// 4. check recursively */
+		// 3.2. check recursively */
 		err := ctl.checkAndFormat(childService)
 		if err != nil {
 			return err