diff --git a/core/src/main/java/io/substrait/type/TypeVisitor.java b/core/src/main/java/io/substrait/type/TypeVisitor.java
index d76b7a1f9..ba06dbd49 100644
--- a/core/src/main/java/io/substrait/type/TypeVisitor.java
+++ b/core/src/main/java/io/substrait/type/TypeVisitor.java
@@ -1,75 +1,304 @@
 package io.substrait.type;
 
+/**
+ * Visitor over the concrete {@link Type} kinds.
+ *
+ * @param <R> the result type produced by the visitor
+ * @param <E> the exception type that may be thrown
+ */
 public interface TypeVisitor<R, E extends Throwable> {
+  /**
+   * Visits a boolean type.
+   *
+   * @param type the type being visited
+   * @return the visit result
+   * @throws E if the visit fails
+   */
   R visit(Type.Bool type) throws E;
 
+  /**
+   * Visits an 8-bit integer type.
+   *
+   * @param type the type being visited
+   * @return the visit result
+   * @throws E if the visit fails
+   */
   R visit(Type.I8 type) throws E;
 
+  /**
+   * Visits a 16-bit integer type.
+   *
+   * @param type the type being visited
+   * @return the visit result
+   * @throws E if the visit fails
+   */
   R visit(Type.I16 type) throws E;
 
+  /**
+   * Visits a 32-bit integer type.
+   *
+   * @param type the type being visited
+   * @return the visit result
+   * @throws E if the visit fails
+   */
   R visit(Type.I32 type) throws E;
 
+  /**
+   * Visits a 64-bit integer type.
+   *
+   * @param type the type being visited
+   * @return the visit result
+   * @throws E if the visit fails
+   */
   R visit(Type.I64 type) throws E;
 
+  /**
+   * Visits a 32-bit floating point type.
+   *
+   * @param type the type being visited
+   * @return the visit result
+   * @throws E if the visit fails
+   */
   R visit(Type.FP32 type) throws E;
 
+  /**
+   * Visits a 64-bit floating point type.
+   *
+   * @param type the type being visited
+   * @return the visit result
+   * @throws E if the visit fails
+   */
   R visit(Type.FP64 type) throws E;
 
+  /**
+   * Visits a string type.
+   *
+   * @param type the type being visited
+   * @return the visit result
+   * @throws E if the visit fails
+   */
   R visit(Type.Str type) throws E;
 
+  /**
+   * Visits a binary type.
+   *
+   * @param type the type being visited
+   * @return the visit result
+   * @throws E if the visit fails
+   */
   R visit(Type.Binary type) throws E;
 
+  /**
+   * Visits a date type.
+   *
+   * @param type the type being visited
+   * @return the visit result
+   * @throws E if the visit fails
+   */
   R visit(Type.Date type) throws E;
 
+  /**
+   * Visits a time type.
+   *
+   * @param type the type being visited
+   * @return the visit result
+   * @throws E if the visit fails
+   * @deprecated use {@link #visit(Type.PrecisionTime)} instead
+   */
   @Deprecated
   R visit(Type.Time type) throws E;
 
+  /**
+   * Visits a timestamp with timezone type.
+   *
+   * @param type the type being visited
+   * @return the visit result
+   * @throws E if the visit fails
+   * @deprecated use {@link #visit(Type.PrecisionTimestampTZ)} instead
+   */
   @Deprecated
   R visit(Type.TimestampTZ type) throws E;
 
+  /**
+   * Visits a timestamp (without timezone) type.
+   *
+   * @param type the type being visited
+   * @return the visit result
+   * @throws E if the visit fails
+   * @deprecated use {@link #visit(Type.PrecisionTimestamp)} instead
+   */
   @Deprecated
   R visit(Type.Timestamp type) throws E;
 
+  /**
+   * Visits a precision-time type.
+   *
+   * @param type the type being visited
+   * @return the visit result
+   * @throws E if the visit fails
+   */
   R visit(Type.PrecisionTime type) throws E;
 
+  /**
+   * Visits a precision-timestamp (without timezone) type.
+   *
+   * @param type the type being visited
+   * @return the visit result
+   * @throws E if the visit fails
+   */
   R visit(Type.PrecisionTimestamp type) throws E;
 
+  /**
+   * Visits a precision-timestamp with timezone type.
+   *
+   * @param type the type being visited
+   * @return the visit result
+   * @throws E if the visit fails
+   */
   R visit(Type.PrecisionTimestampTZ type) throws E;
 
+  /**
+   * Visits a year-month interval type.
+   *
+   * @param type the type being visited
+   * @return the visit result
+   * @throws E if the visit fails
+   */
   R visit(Type.IntervalYear type) throws E;
 
+  /**
+   * Visits a day-time interval type.
+   *
+   * @param type the type being visited
+   * @return the visit result
+   * @throws E if the visit fails
+   */
   R visit(Type.IntervalDay type) throws E;
 
+  /**
+   * Visits a compound interval type.
+   *
+   * @param type the type being visited
+   * @return the visit result
+   * @throws E if the visit fails
+   */
   R visit(Type.IntervalCompound type) throws E;
 
+  /**
+   * Visits a UUID type.
+   *
+   * @param type the type being visited
+   * @return the visit result
+   * @throws E if the visit fails
+   */
   R visit(Type.UUID type) throws E;
 
+  /**
+   * Visits a fixed-length character type.
+   *
+   * @param type the type being visited
+   * @return the visit result
+   * @throws E if the visit fails
+   */
   R visit(Type.FixedChar type) throws E;
 
+  /**
+   * Visits a variable-length character type.
+   *
+   * @param type the type being visited
+   * @return the visit result
+   * @throws E if the visit fails
+   */
   R visit(Type.VarChar type) throws E;
 
+  /**
+   * Visits a fixed-length binary type.
+   *
+   * @param type the type being visited
+   * @return the visit result
+   * @throws E if the visit fails
+   */
   R visit(Type.FixedBinary type) throws E;
 
+  /**
+   * Visits a decimal type.
+   *
+   * @param type the type being visited
+   * @return the visit result
+   * @throws E if the visit fails
+   */
   R visit(Type.Decimal type) throws E;
 
+  /**
+   * Visits a function type.
+   *
+   * @param type the type being visited
+   * @return the visit result
+   * @throws E if the visit fails
+   */
   R visit(Type.Func type) throws E;
 
+  /**
+   * Visits a struct type.
+   *
+   * @param type the type being visited
+   * @return the visit result
+   * @throws E if the visit fails
+   */
   R visit(Type.Struct type) throws E;
 
+  /**
+   * Visits a list type.
+   *
+   * @param type the type being visited
+   * @return the visit result
+   * @throws E if the visit fails
+   */
   R visit(Type.ListType type) throws E;
 
+  /**
+   * Visits a map type.
+   *
+   * @param type the type being visited
+   * @return the visit result
+   * @throws E if the visit fails
+   */
   R visit(Type.Map type) throws E;
 
+  /**
+   * Visits a user-defined type.
+   *
+   * @param type the type being visited
+   * @return the visit result
+   * @throws E if the visit fails
+   */
   R visit(Type.UserDefined type) throws E;
 
+  /**
+   * Base {@link TypeVisitor} that throws {@link UnsupportedOperationException} for every type,
+   * allowing subclasses to override only the visit methods they support.
+   *
+   * @param <R> the result type produced by the visitor
+   * @param <E> the exception type that may be thrown
+   */
   abstract class TypeThrowsVisitor<R, E extends Throwable> implements TypeVisitor<R, E> {
 
     private final String unsupportedMessage;
 
+    /**
+     * Creates a visitor that throws with the given message for unsupported types.
+     *
+     * @param unsupportedMessage the message used for unsupported types
+     */
     protected TypeThrowsVisitor(String unsupportedMessage) {
       this.unsupportedMessage = unsupportedMessage;
     }
 
+    /**
+     * Throws an {@link UnsupportedOperationException} with the configured message.
+     *
+     * @return never returns; always throws
+     */
     protected final UnsupportedOperationException t() {
       throw new UnsupportedOperationException(unsupportedMessage);
     }