diff --git a/addons/project/kateprojectcodeanalysistool.h b/addons/project/kateprojectcodeanalysistool.h
--- a/addons/project/kateprojectcodeanalysistool.h
+++ b/addons/project/kateprojectcodeanalysistool.h
@@ -54,6 +54,15 @@
      */
     virtual QString name() = 0;
 
+    /**
+     * @returns a string containing the file extensions this
+     * tool should be run, separated by '|',
+     * e.g. "cpp|cxx"
+     * NOTE that this is used directly as part of a regular expression.
+     * If more flexibility is required this method probably will change
+     */
+    virtual QString fileExtensions() = 0;
+
     /**
      * filter relevant files
      * @param files set of files in project
diff --git a/addons/project/kateprojectinfoviewcodeanalysis.h b/addons/project/kateprojectinfoviewcodeanalysis.h
--- a/addons/project/kateprojectinfoviewcodeanalysis.h
+++ b/addons/project/kateprojectinfoviewcodeanalysis.h
@@ -23,10 +23,11 @@
 
 #include "kateproject.h"
 
-#include <QPushButton>
+#include <QComboBox>
+#include <QLabel>
 #include <QProcess>
+#include <QPushButton>
 #include <QTreeView>
-#include <QComboBox>
 
 class KateProjectPluginView;
 class KateProjectCodeAnalysisTool;
@@ -62,6 +63,11 @@
     }
 
 private Q_SLOTS:
+    /**
+     * Called if the tool is changed (currently via Combobox)
+     */
+    void slotToolSelectionChanged(int);
+
     /**
      * Called if start/stop button is clicked.
      */
@@ -121,10 +127,20 @@
      */
     QProcess *m_analyzer;
 
+    /**
+     * currently selected tool
+     */
     KateProjectCodeAnalysisTool *m_analysisTool;
 
+    /**
+     * UI element to select the tool
+     */
     QComboBox *m_toolSelector;
 
+    /**
+     * contains a rich text to explain what the current tool does
+     */
+    QString m_toolInfoText;
 };
 
 #endif
diff --git a/addons/project/kateprojectinfoviewcodeanalysis.cpp b/addons/project/kateprojectinfoviewcodeanalysis.cpp
--- a/addons/project/kateprojectinfoviewcodeanalysis.cpp
+++ b/addons/project/kateprojectinfoviewcodeanalysis.cpp
@@ -23,9 +23,10 @@
 #include "kateprojectcodeanalysistool.h"
 #include "tools/kateprojectcodeanalysisselector.h"
 
-#include <QVBoxLayout>
-#include <QHBoxLayout>
 #include <QFileInfo>
+#include <QHBoxLayout>
+#include <QVBoxLayout>
+#include <QToolTip>
 
 #include <klocalizedstring.h>
 #include <kmessagewidget.h>
@@ -63,22 +64,34 @@
     m_treeView->sortByColumn(2, Qt::AscendingOrder);
 
     /**
-     * attach model to code analysis selector
+     * Connect selection change callback
+     * and attach model to code analysis selector
      */
+    connect(m_toolSelector, static_cast<void(QComboBox::*)(int)>(&QComboBox::currentIndexChanged),
+            this, &KateProjectInfoViewCodeAnalysis::slotToolSelectionChanged);
     m_toolSelector->setModel(KateProjectCodeAnalysisSelector::model(this));
 
     /**
      * layout widget
      */
     QVBoxLayout *layout = new QVBoxLayout;
     layout->setSpacing(0);
-    layout->addWidget(m_treeView);
+    // top: selector and buttons...
     QHBoxLayout *hlayout = new QHBoxLayout;
     layout->addLayout(hlayout);
     hlayout->setSpacing(0);
-    hlayout->addStretch();
     hlayout->addWidget(m_toolSelector);
+    auto infoButton = new QPushButton(QIcon::fromTheme(QStringLiteral("documentinfo")), QString(), this);
+    infoButton->setFocusPolicy(Qt::FocusPolicy::TabFocus);
+    connect(infoButton, &QPushButton::clicked, this,
+            [this]() {
+                QToolTip::showText(QCursor::pos(), m_toolInfoText);
+            });
+    hlayout->addWidget(infoButton);
     hlayout->addWidget(m_startStopAnalysis);
+    hlayout->addStretch();
+    // below: result list...
+    layout->addWidget(m_treeView);
     setLayout(layout);
 
     /**
@@ -92,6 +105,13 @@
 {
 }
 
+void KateProjectInfoViewCodeAnalysis::slotToolSelectionChanged(int)
+{
+    m_analysisTool = m_toolSelector->currentData(Qt::UserRole + 1).value<KateProjectCodeAnalysisTool*>();
+    m_toolInfoText = i18n("The selected tool will be run on all project files which match this list of file extensions:<br/><b>%1</b>",
+                            m_analysisTool->fileExtensions());
+}
+
 void KateProjectInfoViewCodeAnalysis::slotStartStopClicked()
 {
     /**
@@ -128,7 +148,7 @@
         m_messageWidget->setMessageType(KMessageWidget::Warning);
         m_messageWidget->setWordWrap(false);
         m_messageWidget->setText(m_analysisTool->notInstalledMessage());
-        static_cast<QVBoxLayout *>(layout())->insertWidget(0, m_messageWidget);
+        static_cast<QVBoxLayout *>(layout())->addWidget(m_messageWidget);
         m_messageWidget->animatedShow();
         return;
     }
@@ -223,6 +243,6 @@
     m_messageWidget->setMessageType(KMessageWidget::Warning);
     m_messageWidget->setText(i18n("Analysis failed!"));
   }
-  static_cast<QVBoxLayout*>(layout ())->insertWidget(0, m_messageWidget);
+  static_cast<QVBoxLayout*>(layout ())->addWidget(m_messageWidget);
   m_messageWidget->animatedShow ();
 }
diff --git a/addons/project/tools/kateprojectcodeanalysistoolcppcheck.h b/addons/project/tools/kateprojectcodeanalysistoolcppcheck.h
--- a/addons/project/tools/kateprojectcodeanalysistoolcppcheck.h
+++ b/addons/project/tools/kateprojectcodeanalysistoolcppcheck.h
@@ -35,6 +35,8 @@
 
     virtual QString name() override;
 
+    virtual QString fileExtensions() override;
+
     virtual QStringList filter(const QStringList &files) override;
 
     virtual QString path() override;
diff --git a/addons/project/tools/kateprojectcodeanalysistoolcppcheck.cpp b/addons/project/tools/kateprojectcodeanalysistoolcppcheck.cpp
--- a/addons/project/tools/kateprojectcodeanalysistoolcppcheck.cpp
+++ b/addons/project/tools/kateprojectcodeanalysistoolcppcheck.cpp
@@ -39,10 +39,17 @@
     return i18n("cppcheck");
 }
 
+QString KateProjectCodeAnalysisToolCppcheck::fileExtensions()
+{
+    return QStringLiteral("cpp|cxx|cc|c++|c|tpp|txx");
+}
+
 QStringList KateProjectCodeAnalysisToolCppcheck::filter(const QStringList &files)
 {
     // c++ files
-    return files.filter(QRegularExpression(QStringLiteral("\\.(cpp|cxx|cc|c\\+\\+|c|tpp|txx)$")));
+    return files.filter(QRegularExpression(QStringLiteral("\\.(")
+    + fileExtensions().replace(QStringLiteral("+"), QStringLiteral("\\+"))
+    + QStringLiteral(")$")));
 }
 
 QString KateProjectCodeAnalysisToolCppcheck::path()
diff --git a/addons/project/tools/kateprojectcodeanalysistoolflake8.h b/addons/project/tools/kateprojectcodeanalysistoolflake8.h
--- a/addons/project/tools/kateprojectcodeanalysistoolflake8.h
+++ b/addons/project/tools/kateprojectcodeanalysistoolflake8.h
@@ -35,6 +35,8 @@
 
     virtual QString name() override;
 
+    virtual QString fileExtensions() override;
+
     virtual QStringList filter(const QStringList &files) override;
 
     virtual QString path() override;
diff --git a/addons/project/tools/kateprojectcodeanalysistoolflake8.cpp b/addons/project/tools/kateprojectcodeanalysistoolflake8.cpp
--- a/addons/project/tools/kateprojectcodeanalysistoolflake8.cpp
+++ b/addons/project/tools/kateprojectcodeanalysistoolflake8.cpp
@@ -39,10 +39,15 @@
     return i18n("flake8");
 }
 
+QString KateProjectCodeAnalysisToolFlake8::fileExtensions()
+{
+    return QStringLiteral("py");
+}
+
 QStringList KateProjectCodeAnalysisToolFlake8::filter(const QStringList &files)
 {
     // for now we expect files with extension
-    return files.filter(QRegularExpression(QStringLiteral("\\.py$")));
+    return files.filter(QRegularExpression(QStringLiteral("\\.(") + fileExtensions() + QStringLiteral(")$")));
 }
 
 QString KateProjectCodeAnalysisToolFlake8::path()