docs: add missing KDoc comments for public functions, properties, and classes (#621)

kotlin-sdk-core/src/commonMain/kotlin/io/modelcontextprotocol/kotlin/sdk/shared/ReadBuffer.kt

@@ -16,6 +16,7 @@ public class ReadBuffer {
 
     private val buffer: Buffer = Buffer()
 
+    /** Appends raw bytes to the internal buffer for subsequent message parsing. */
     public fun append(chunk: ByteArray) {
         buffer.write(chunk)
     }
@@ -86,6 +87,7 @@ public class ReadBuffer {
         }
     }
 
+    /** Clears all buffered data, discarding any partially received messages. */
     public fun clear() {
         buffer.clear()
     }
@@ -93,4 +95,5 @@ public class ReadBuffer {
 
 internal fun deserializeMessage(line: String): JSONRPCMessage = McpJson.decodeFromString<JSONRPCMessage>(line)
 
+/** Serializes a [JSONRPCMessage] to its JSON string representation with a trailing newline. */
 public fun serializeMessage(message: JSONRPCMessage): String = McpJson.encodeToString(message) + "\n"

kotlin-sdk-core/src/commonMain/kotlin/io/modelcontextprotocol/kotlin/sdk/types/capabilities.dsl.kt

@@ -171,6 +171,7 @@ public class ClientCapabilitiesBuilder @PublishedApi internal constructor() {
      */
     public fun experimental(block: JsonObjectBuilder.() -> Unit): Unit = experimental(buildJsonObject(block))
 
+    /** Constructs the [ClientCapabilities] instance from the current builder state. */
     @PublishedApi
     internal fun build(): ClientCapabilities = ClientCapabilities(
         sampling = sampling,

kotlin-sdk-core/src/commonMain/kotlin/io/modelcontextprotocol/kotlin/sdk/types/common.kt

@@ -41,8 +41,10 @@ public sealed interface WithMeta {
  */
 public typealias ProgressToken = RequestId
 
+/** Creates a [ProgressToken] from a string value. */
 public fun ProgressToken(value: String): ProgressToken = RequestId(value)
 
+/** Creates a [ProgressToken] from a numeric value. */
 public fun ProgressToken(value: Long): ProgressToken = RequestId(value)
 
 // ============================================================================
@@ -127,6 +129,7 @@ public sealed interface Reference {
     public val type: ReferenceType
 }
 
+/** Discriminator for [Reference] subtypes used in completion and other operations. */
 @Serializable
 public enum class ReferenceType(public val value: String) {
     @SerialName("ref/prompt")

kotlin-sdk-core/src/commonMain/kotlin/io/modelcontextprotocol/kotlin/sdk/types/content.dsl.kt

@@ -88,6 +88,7 @@ public abstract class MediaContentBuilder {
         meta = buildJsonObject(block)
     }
 
+    /** Constructs the [MediaContent] instance from the current builder state. */
     @PublishedApi
     internal abstract fun build(): MediaContent
 }

kotlin-sdk-core/src/commonMain/kotlin/io/modelcontextprotocol/kotlin/sdk/types/content.kt

@@ -8,6 +8,7 @@ import kotlinx.serialization.SerialName
 import kotlinx.serialization.Serializable
 import kotlinx.serialization.json.JsonObject
 
+/** Discriminator values for the polymorphic [ContentBlock] hierarchy. */
 @Serializable
 public enum class ContentTypes(public val value: String) {
     @SerialName("text")

kotlin-sdk-core/src/commonMain/kotlin/io/modelcontextprotocol/kotlin/sdk/types/jsonRpc.kt

@@ -40,10 +40,12 @@ public fun RequestId(value: Long): RequestId = RequestId.NumberId(value)
 @Serializable(with = RequestIdPolymorphicSerializer::class)
 public sealed interface RequestId {
 
+    /** A string-based request identifier. */
     @JvmInline
     @Serializable
     public value class StringId(public val value: String) : RequestId
 
+    /** A numeric request identifier. */
     @JvmInline
     @Serializable
     public value class NumberId(public val value: Long) : RequestId

kotlin-sdk-core/src/commonMain/kotlin/io/modelcontextprotocol/kotlin/sdk/types/sampling.kt

@@ -243,6 +243,7 @@ public data class CreateMessageResult(
     override val meta: JsonObject? = null,
 ) : ClientResult
 
+/** The reason why the LLM stopped generating tokens. */
 @JvmInline
 @Serializable
 public value class StopReason(public val value: String) {