modelcontextprotocol/kotlin-sdk
Watch
1
0
Fork
You've already forked kotlin-sdk
 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions 1

feat(core): add extensions field to ClientCapabilities and ServerCapabilities (#678)

Browse source 
<!-- Provide a brief summary of your changes -->

Add support for MCP extension negotiation during the initialize
handshake, as defined in the MCP extensions specification. Clients and
servers can now advertise supported extensions via a new `extensions:
Map<String, JsonObject>?` field on their respective capabilities
objects.

## Motivation and Context
<!-- Why is this change needed? What problem does it solve? -->
Extensions are supported part of the [MCP spec
](https://modelcontextprotocol.io/extensions/overview) and are available
in other language libraries e.g. [Golang
](862d78a265/mcp/protocol.go (L215)).

## How Has This Been Tested?
Existing and added unit tests

## Breaking Changes
<!-- Will users need to update their code or configurations? -->
Adding a new field to existing ClientCapabilities and ServerCapabilities
fields will break already compiled clients. They will need to recompile
on upgrading.

## Types of changes
<!-- What types of changes does your code introduce? Put an `x` in all
the boxes that apply: -->
- [ ] Bug fix (non-breaking change which fixes an issue)
- [x] New feature (non-breaking change which adds functionality)
- [ ] Breaking change (fix or feature that would cause existing
functionality to change)
- [ ] Documentation update

## Checklist
<!-- Go over all the following points, and put an `x` in all the boxes
that apply. -->
- [x] I have read the [MCP
Documentation](https://modelcontextprotocol.io)
- [x] My code follows the repository's style guidelines
- [x] New and existing tests pass locally
- [x] I have added appropriate error handling
- [x] I have added or updated documentation as needed

## Additional context
<!-- Add any other context, implementation notes, or design decisions
-->

Co-authored-by: Pavel Gorgulov <devcrocod@gmail.com>
This commit is contained in:
Evan 2026-04-23 10:22:18 -04:00 • committed by GitHub
commit bf8dc6d6b1
No known key found for this signature in database
GPG key ID: B5690EEEBB952194
1 changed files with 217 additions and 8 deletions
Download patch file Download diff file Expand all files Collapse all files

21
kotlin-sdk-core/api/kotlin-sdk-core.api
View file

@ -606,17 +606,19 @@ public final class io/modelcontextprotocol/kotlin/sdk/types/CancelledNotificatio
public final class io/modelcontextprotocol/kotlin/sdk/types/ClientCapabilities {
public static final field Companion Lio/modelcontextprotocol/kotlin/sdk/types/ClientCapabilities$Companion;
public fun <init> ()V
public fun <init> (Lkotlinx/serialization/json/JsonObject;Lio/modelcontextprotocol/kotlin/sdk/types/ClientCapabilities$Roots;Lkotlinx/serialization/json/JsonObject;Lkotlinx/serialization/json/JsonObject;)V
public synthetic fun <init> (Lkotlinx/serialization/json/JsonObject;Lio/modelcontextprotocol/kotlin/sdk/types/ClientCapabilities$Roots;Lkotlinx/serialization/json/JsonObject;Lkotlinx/serialization/json/JsonObject;ILkotlin/jvm/internal/DefaultConstructorMarker;)V
public fun <init> (Lkotlinx/serialization/json/JsonObject;Lio/modelcontextprotocol/kotlin/sdk/types/ClientCapabilities$Roots;Lkotlinx/serialization/json/JsonObject;Lkotlinx/serialization/json/JsonObject;Ljava/util/Map;)V
public synthetic fun <init> (Lkotlinx/serialization/json/JsonObject;Lio/modelcontextprotocol/kotlin/sdk/types/ClientCapabilities$Roots;Lkotlinx/serialization/json/JsonObject;Lkotlinx/serialization/json/JsonObject;Ljava/util/Map;ILkotlin/jvm/internal/DefaultConstructorMarker;)V
public final fun component1 ()Lkotlinx/serialization/json/JsonObject;
public final fun component2 ()Lio/modelcontextprotocol/kotlin/sdk/types/ClientCapabilities$Roots;
public final fun component3 ()Lkotlinx/serialization/json/JsonObject;
public final fun component4 ()Lkotlinx/serialization/json/JsonObject;
public final fun copy (Lkotlinx/serialization/json/JsonObject;Lio/modelcontextprotocol/kotlin/sdk/types/ClientCapabilities$Roots;Lkotlinx/serialization/json/JsonObject;Lkotlinx/serialization/json/JsonObject;)Lio/modelcontextprotocol/kotlin/sdk/types/ClientCapabilities;
public static synthetic fun copy$default (Lio/modelcontextprotocol/kotlin/sdk/types/ClientCapabilities;Lkotlinx/serialization/json/JsonObject;Lio/modelcontextprotocol/kotlin/sdk/types/ClientCapabilities$Roots;Lkotlinx/serialization/json/JsonObject;Lkotlinx/serialization/json/JsonObject;ILjava/lang/Object;)Lio/modelcontextprotocol/kotlin/sdk/types/ClientCapabilities;
public final fun component5 ()Ljava/util/Map;
public final fun copy (Lkotlinx/serialization/json/JsonObject;Lio/modelcontextprotocol/kotlin/sdk/types/ClientCapabilities$Roots;Lkotlinx/serialization/json/JsonObject;Lkotlinx/serialization/json/JsonObject;Ljava/util/Map;)Lio/modelcontextprotocol/kotlin/sdk/types/ClientCapabilities;
public static synthetic fun copy$default (Lio/modelcontextprotocol/kotlin/sdk/types/ClientCapabilities;Lkotlinx/serialization/json/JsonObject;Lio/modelcontextprotocol/kotlin/sdk/types/ClientCapabilities$Roots;Lkotlinx/serialization/json/JsonObject;Lkotlinx/serialization/json/JsonObject;Ljava/util/Map;ILjava/lang/Object;)Lio/modelcontextprotocol/kotlin/sdk/types/ClientCapabilities;
public fun equals (Ljava/lang/Object;)Z
public final fun getElicitation ()Lkotlinx/serialization/json/JsonObject;
public final fun getExperimental ()Lkotlinx/serialization/json/JsonObject;
public final fun getExtensions ()Ljava/util/Map;
public final fun getRoots ()Lio/modelcontextprotocol/kotlin/sdk/types/ClientCapabilities$Roots;
public final fun getSampling ()Lkotlinx/serialization/json/JsonObject;
public fun hashCode ()I
@ -676,6 +678,7 @@ public final class io/modelcontextprotocol/kotlin/sdk/types/ClientCapabilitiesBu
public final fun elicitation (Lkotlinx/serialization/json/JsonObject;)V
public final fun experimental (Lkotlin/jvm/functions/Function1;)V
public final fun experimental (Lkotlinx/serialization/json/JsonObject;)V
public final fun extensions (Ljava/util/Map;)V
public final fun roots (Ljava/lang/Boolean;)V
public static synthetic fun roots$default (Lio/modelcontextprotocol/kotlin/sdk/types/ClientCapabilitiesBuilder;Ljava/lang/Boolean;ILjava/lang/Object;)V
public final fun sampling (Lkotlin/jvm/functions/Function1;)V
@ -4245,19 +4248,21 @@ public final class io/modelcontextprotocol/kotlin/sdk/types/Sampling_dslKt {
public final class io/modelcontextprotocol/kotlin/sdk/types/ServerCapabilities {
public static final field Companion Lio/modelcontextprotocol/kotlin/sdk/types/ServerCapabilities$Companion;
public fun <init> ()V
public fun <init> (Lio/modelcontextprotocol/kotlin/sdk/types/ServerCapabilities$Tools;Lio/modelcontextprotocol/kotlin/sdk/types/ServerCapabilities$Resources;Lio/modelcontextprotocol/kotlin/sdk/types/ServerCapabilities$Prompts;Lkotlinx/serialization/json/JsonObject;Lkotlinx/serialization/json/JsonObject;Lkotlinx/serialization/json/JsonObject;)V
public synthetic fun <init> (Lio/modelcontextprotocol/kotlin/sdk/types/ServerCapabilities$Tools;Lio/modelcontextprotocol/kotlin/sdk/types/ServerCapabilities$Resources;Lio/modelcontextprotocol/kotlin/sdk/types/ServerCapabilities$Prompts;Lkotlinx/serialization/json/JsonObject;Lkotlinx/serialization/json/JsonObject;Lkotlinx/serialization/json/JsonObject;ILkotlin/jvm/internal/DefaultConstructorMarker;)V
public fun <init> (Lio/modelcontextprotocol/kotlin/sdk/types/ServerCapabilities$Tools;Lio/modelcontextprotocol/kotlin/sdk/types/ServerCapabilities$Resources;Lio/modelcontextprotocol/kotlin/sdk/types/ServerCapabilities$Prompts;Lkotlinx/serialization/json/JsonObject;Lkotlinx/serialization/json/JsonObject;Lkotlinx/serialization/json/JsonObject;Ljava/util/Map;)V
public synthetic fun <init> (Lio/modelcontextprotocol/kotlin/sdk/types/ServerCapabilities$Tools;Lio/modelcontextprotocol/kotlin/sdk/types/ServerCapabilities$Resources;Lio/modelcontextprotocol/kotlin/sdk/types/ServerCapabilities$Prompts;Lkotlinx/serialization/json/JsonObject;Lkotlinx/serialization/json/JsonObject;Lkotlinx/serialization/json/JsonObject;Ljava/util/Map;ILkotlin/jvm/internal/DefaultConstructorMarker;)V
public final fun component1 ()Lio/modelcontextprotocol/kotlin/sdk/types/ServerCapabilities$Tools;
public final fun component2 ()Lio/modelcontextprotocol/kotlin/sdk/types/ServerCapabilities$Resources;
public final fun component3 ()Lio/modelcontextprotocol/kotlin/sdk/types/ServerCapabilities$Prompts;
public final fun component4 ()Lkotlinx/serialization/json/JsonObject;
public final fun component5 ()Lkotlinx/serialization/json/JsonObject;
public final fun component6 ()Lkotlinx/serialization/json/JsonObject;
public final fun copy (Lio/modelcontextprotocol/kotlin/sdk/types/ServerCapabilities$Tools;Lio/modelcontextprotocol/kotlin/sdk/types/ServerCapabilities$Resources;Lio/modelcontextprotocol/kotlin/sdk/types/ServerCapabilities$Prompts;Lkotlinx/serialization/json/JsonObject;Lkotlinx/serialization/json/JsonObject;Lkotlinx/serialization/json/JsonObject;)Lio/modelcontextprotocol/kotlin/sdk/types/ServerCapabilities;
public static synthetic fun copy$default (Lio/modelcontextprotocol/kotlin/sdk/types/ServerCapabilities;Lio/modelcontextprotocol/kotlin/sdk/types/ServerCapabilities$Tools;Lio/modelcontextprotocol/kotlin/sdk/types/ServerCapabilities$Resources;Lio/modelcontextprotocol/kotlin/sdk/types/ServerCapabilities$Prompts;Lkotlinx/serialization/json/JsonObject;Lkotlinx/serialization/json/JsonObject;Lkotlinx/serialization/json/JsonObject;ILjava/lang/Object;)Lio/modelcontextprotocol/kotlin/sdk/types/ServerCapabilities;
public final fun component7 ()Ljava/util/Map;
public final fun copy (Lio/modelcontextprotocol/kotlin/sdk/types/ServerCapabilities$Tools;Lio/modelcontextprotocol/kotlin/sdk/types/ServerCapabilities$Resources;Lio/modelcontextprotocol/kotlin/sdk/types/ServerCapabilities$Prompts;Lkotlinx/serialization/json/JsonObject;Lkotlinx/serialization/json/JsonObject;Lkotlinx/serialization/json/JsonObject;Ljava/util/Map;)Lio/modelcontextprotocol/kotlin/sdk/types/ServerCapabilities;
public static synthetic fun copy$default (Lio/modelcontextprotocol/kotlin/sdk/types/ServerCapabilities;Lio/modelcontextprotocol/kotlin/sdk/types/ServerCapabilities$Tools;Lio/modelcontextprotocol/kotlin/sdk/types/ServerCapabilities$Resources;Lio/modelcontextprotocol/kotlin/sdk/types/ServerCapabilities$Prompts;Lkotlinx/serialization/json/JsonObject;Lkotlinx/serialization/json/JsonObject;Lkotlinx/serialization/json/JsonObject;Ljava/util/Map;ILjava/lang/Object;)Lio/modelcontextprotocol/kotlin/sdk/types/ServerCapabilities;
public fun equals (Ljava/lang/Object;)Z
public final fun getCompletions ()Lkotlinx/serialization/json/JsonObject;
public final fun getExperimental ()Lkotlinx/serialization/json/JsonObject;
public final fun getExtensions ()Ljava/util/Map;
public final fun getLogging ()Lkotlinx/serialization/json/JsonObject;
public final fun getPrompts ()Lio/modelcontextprotocol/kotlin/sdk/types/ServerCapabilities$Prompts;
public final fun getResources ()Lio/modelcontextprotocol/kotlin/sdk/types/ServerCapabilities$Resources;