modelcontextprotocol/kotlin-sdk

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The official Kotlin SDK for Model Context Protocol servers and clients. Maintained in collaboration with JetBrains

Stars: 1.5k
Forks: 248
Open beginner issues: 0
Indexed issues: 78
Avg merge: 1d 20h
Merged PRs (30d): 23

Dominant language: Kotlin
License: No license data
Last GitHub push: Sep 18, 2026
Latest indexed: Sep 20, 2026
Contributing guide: Contributing guide
Code of conduct: Code of conduct
Beginner labels: help wanted

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78 open issues indexed

[Proposal] SEP-2351: Explicit RFC 8414 well-known URI suffix specification & client discovery (#810) Open

Difficulty 5/5 Over a week Newbie friendliness 35/100

modelcontextprotocol/kotlin-sdk#1009 · Opened Sep 18, 2026
[Proposal] Provide ServerSession in onConnect & global notification handler callbacks (#780) Open

Difficulty 5/5 Over a week Newbie friendliness 45/100

modelcontextprotocol/kotlin-sdk#1008 · Opened Sep 18, 2026
[Proposal] SEP-1865: MCP Apps (Interactive User Interfaces) architecture & SDK integration design (#802) Open

Difficulty 5/5 Over a week Newbie friendliness 35/100

modelcontextprotocol/kotlin-sdk#1007 · Opened Sep 18, 2026
[Proposal] SEP-2133: Extensions framework architecture & integration design (#804) Open

Difficulty 5/5 Over a week Newbie friendliness 30/100

modelcontextprotocol/kotlin-sdk#1006 · Opened Sep 18, 2026
[Proposal] SEP-2322: Multi Round-Trip Requests (MRTR) architecture & flow design (#808) Open

Difficulty 5/5 Over a week Newbie friendliness 28/100

modelcontextprotocol/kotlin-sdk#1005 · Opened Sep 18, 2026
[Proposal] SEP-2567: Sessionless MCP via Explicit State Handles architecture & migration design (#814) Open

Difficulty 5/5 Over a week Newbie friendliness 25/100

modelcontextprotocol/kotlin-sdk#1004 · Opened Sep 18, 2026
[Proposal] SEP-2663: Tasks Extension architecture & migration design (#817) Open

Difficulty 5/5 Over a week Newbie friendliness 35/100

modelcontextprotocol/kotlin-sdk#1003 · Opened Sep 18, 2026
[Proposal] SEP-2260: Require Server requests to be associated with Client requests (#807) Open

Difficulty 5/5 Over a week Newbie friendliness 35/100

modelcontextprotocol/kotlin-sdk#1002 · Opened Sep 18, 2026
[Proposal] SEP-2549: TTL for List Results implementation design (#813) Open

Difficulty 5/5 Over a week Newbie friendliness 35/100

modelcontextprotocol/kotlin-sdk#1001 · Opened Sep 18, 2026
[Proposal] SEP-414: OpenTelemetry Trace Context Propagation design (#800) Open

Difficulty 5/5 Over a week Newbie friendliness 35/100

modelcontextprotocol/kotlin-sdk#1000 · Opened Sep 18, 2026
Support Android targets for remote MCP clients Open

enhancement

Difficulty 5/5 Over a week Newbie friendliness 38/100

modelcontextprotocol/kotlin-sdk#972 · Opened Aug 24, 2026
StdioServerTransport fails to deserialize initial message when stdin starts with UTF-8 BOM Open

bug P2 ready for work

Difficulty 3/5 1-2 days Newbie friendliness 74/100

modelcontextprotocol/kotlin-sdk#956 · 1 comment · Opened Aug 15, 2026
Stateful StreamableHttpServerTransport leaks the standalone GET SSE stream on session close Open

bug P1 ready for work

Difficulty 2/5 1-3 hours Newbie friendliness 72/100

modelcontextprotocol/kotlin-sdk#922 · Opened Jul 30, 2026
Ktor SSE / StreamableHttp extensions build their transports internally, with no hook to wrap them Open

api enhancement P2 ready for work

Difficulty 5/5 Over a week Newbie friendliness 42/100

modelcontextprotocol/kotlin-sdk#921 · Opened Jul 27, 2026
ServerSession.onInitialized has no state replay, so late registrants silently miss the event Open

api bug P2 ready for work

Difficulty 4/5 3-5 days Newbie friendliness 56/100

modelcontextprotocol/kotlin-sdk#920 · 2 comments · Opened Jul 27, 2026
onClose callbacks are synchronous, so suspending cleanup has nowhere to run Open

api breaking enhancement P2 ready for work

Difficulty 4/5 3-5 days Newbie friendliness 45/100

modelcontextprotocol/kotlin-sdk#919 · Opened Jul 27, 2026
tracking issue for 2026-07-28 Spec implementation Open

api breaking enhancement P2

Difficulty 5/5 Over a week Newbie friendliness 15/100

modelcontextprotocol/kotlin-sdk#842 · Opened Jun 18, 2026
Implement SEP-2663: Tasks Extension Open

api enhancement P2 ready for work

Difficulty 4/5 3-5 days Newbie friendliness 35/100

modelcontextprotocol/kotlin-sdk#817 · Opened Jun 6, 2026
Implement SEP-2577: Deprecate Roots, Sampling, and Logging Open

api breaking enhancement P2 ready for work

Difficulty 4/5 3-5 days Newbie friendliness 35/100

modelcontextprotocol/kotlin-sdk#816 · Opened Jun 6, 2026
Implement SEP-2575: Make MCP Stateless Open

api breaking enhancement P2 ready for work

Difficulty 5/5 Over a week Newbie friendliness 25/100

modelcontextprotocol/kotlin-sdk#815 · Opened Jun 6, 2026
Implement SEP-2549: TTL for List Results Open

api enhancement P3 ready for work

Difficulty 5/5 Over a week Newbie friendliness 35/100

modelcontextprotocol/kotlin-sdk#813 · Opened Jun 6, 2026
Implement SEP-2567: Sessionless MCP via Explicit State Handles Open

api breaking enhancement P2 ready for work

Difficulty 5/5 Over a week Newbie friendliness 30/100

modelcontextprotocol/kotlin-sdk#814 · Opened Jun 6, 2026
Implement SEP-2468: Recommend Issuer (iss) Parameter in MCP Auth Responses Open

enhancement P3 ready for work

Difficulty 4/5 3-5 days Newbie friendliness 35/100

modelcontextprotocol/kotlin-sdk#812 · Opened Jun 6, 2026
Implement SEP-2352: Clarify authorization server binding and migration Open

enhancement P3 ready for work

Difficulty 5/5 Over a week Newbie friendliness 30/100

modelcontextprotocol/kotlin-sdk#811 · Opened Jun 6, 2026
Implement SEP-2351: Explicitly specify RFC 8414 well-known URI suffix for MCP Open

enhancement P3 ready for work

Difficulty 3/5 1-2 days Newbie friendliness 45/100

modelcontextprotocol/kotlin-sdk#810 · Opened Jun 6, 2026
Implement SEP-2350: Clarify client-side scope accumulation in step-up authorization Open

api enhancement P2 ready for work

Difficulty 4/5 3-5 days Newbie friendliness 35/100

modelcontextprotocol/kotlin-sdk#809 · Opened Jun 6, 2026
Implement SEP-2322: Multi Round-Trip Requests Open

api breaking enhancement P2 ready for work

Difficulty 5/5 Over a week Newbie friendliness 30/100

modelcontextprotocol/kotlin-sdk#808 · Opened Jun 6, 2026
Implement SEP-2207: OIDC-flavored refresh token guidance Open

enhancement P3 ready for work

Difficulty 4/5 3-5 days Newbie friendliness 35/100

modelcontextprotocol/kotlin-sdk#806 · Opened Jun 6, 2026
Implement SEP-2260: Require Server requests to be associated with a Client request Open

api enhancement P2 ready for work

Difficulty 4/5 3-5 days Newbie friendliness 35/100

modelcontextprotocol/kotlin-sdk#807 · Opened Jun 6, 2026
Implement SEP-2164: Standardize resource not found error code (-32602) Open

api breaking enhancement P2 ready for work

Difficulty 4/5 3-5 days Newbie friendliness 35/100

modelcontextprotocol/kotlin-sdk#805 · Opened Jun 6, 2026
Implement SEP-2133: Extensions framework for MCP Open

api enhancement P2 ready for work

Difficulty 5/5 Over a week Newbie friendliness 30/100

modelcontextprotocol/kotlin-sdk#804 · Opened Jun 6, 2026
Implement SEP-2106: Tools inputSchema & outputSchema Conform to JSON Schema 2020-12 Open

api enhancement P2

Difficulty 5/5 Over a week Newbie friendliness 35/100

modelcontextprotocol/kotlin-sdk#803 · Opened Jun 6, 2026
Implement SEP-1865: MCP Apps - Interactive User Interfaces for MCP Open

api enhancement P3 ready for work

Difficulty 5/5 Over a week Newbie friendliness 25/100

modelcontextprotocol/kotlin-sdk#802 · Opened Jun 6, 2026
Implement SEP-837: Update authorization spec to clarify client type requirements Open

enhancement P3 ready for work

Difficulty 4/5 3-5 days Newbie friendliness 25/100

modelcontextprotocol/kotlin-sdk#801 · Opened Jun 6, 2026
Implement SEP-414: Document OpenTelemetry Trace Context Propagation Conventions Open

documentation enhancement P3 ready for work

Difficulty 4/5 3-5 days Newbie friendliness 35/100

modelcontextprotocol/kotlin-sdk#800 · Opened Jun 6, 2026
SEP-2243: Send required Mcp-Method/Mcp-Name HTTP headers Open

enhancement P2 ready for work

Difficulty 3/5 1-2 days Newbie friendliness 58/100

modelcontextprotocol/kotlin-sdk#787 · 1 comment · Opened May 29, 2026
The `onConnect` and `setNotificationHandler` callback should provide the `ServerSession` Open

api enhancement P3 ready for work

Difficulty 4/5 3-5 days Newbie friendliness 48/100

modelcontextprotocol/kotlin-sdk#780 · 1 reaction · Opened May 24, 2026
Streamable HTTP server accepts mismatched `MCP-Protocol-Version` header and body `protocolVersion` on `initialize` Open

enhancement needs confirmation P3

Difficulty 5/5 Over a week Newbie friendliness 35/100

modelcontextprotocol/kotlin-sdk#766 · Opened May 16, 2026
GET SSE stream reconnect fails due to stale STANDALONE_SSE_STREAM_ID mapping Open

bug P1

Difficulty 3/5 1-2 days Newbie friendliness 67/100

modelcontextprotocol/kotlin-sdk#715 · Opened Apr 24, 2026
refactor: Decouple MCP JSON serialization from global ContentNegotiation configuration Open

api enhancement P3 ready for work refactoring

Difficulty 4/5 3-5 days Newbie friendliness 50/100

modelcontextprotocol/kotlin-sdk#668 · 1 comment · 2 reactions · Opened Apr 2, 2026
type-unsafe cast in Protocol result deserialization Open

bug P2 ready for work refactoring

Difficulty 4/5 3-5 days Newbie friendliness 35/100

modelcontextprotocol/kotlin-sdk#601 · Opened Mar 12, 2026
roots StateFlow on session Open

api enhancement P3 ready for work

Difficulty 3/5 1-2 days Newbie friendliness 45/100

modelcontextprotocol/kotlin-sdk#586 · Opened Mar 7, 2026
Ktor extensions for StreamableHttpServerTransport Open

api enhancement P2 ready for work

Difficulty 4/5 3-5 days Newbie friendliness 45/100

modelcontextprotocol/kotlin-sdk#562 · 1 comment · Opened Feb 23, 2026
Add a way to register session cleanup actions from server handlers Open

api enhancement P2 ready for work

Difficulty 3/5 1-2 days Newbie friendliness 48/100

modelcontextprotocol/kotlin-sdk#553 · 1 comment · 2 reactions · Opened Feb 20, 2026
Make client information available in server handlers Open

api enhancement P2 ready for work

Difficulty 3/5 1-2 days Newbie friendliness 58/100

modelcontextprotocol/kotlin-sdk#552 · 1 comment · 2 reactions · Opened Feb 20, 2026
split JsonRPCResponse Open

api breaking enhancement P2 ready for work refactoring

Difficulty 3/5 1-2 days Newbie friendliness 35/100

modelcontextprotocol/kotlin-sdk#545 · 1 comment · Opened Feb 19, 2026
Remove deprecated schema DSL builders Open

api breaking P3 ready for work refactoring

Difficulty 3/5 1-2 days Newbie friendliness 45/100

modelcontextprotocol/kotlin-sdk#537 · Opened Feb 19, 2026
refactor: Unify workflow across server transports Open

P3 ready for work refactoring

Difficulty 5/5 Over a week Newbie friendliness 35/100

modelcontextprotocol/kotlin-sdk#518 · Opened Feb 12, 2026
Access the ServerSSESession from inside a request (e.g. CallToolRequest, ClientRequest, etc) Open

api enhancement P2

Difficulty 4/5 3-5 days Newbie friendliness 35/100

modelcontextprotocol/kotlin-sdk#494 · Opened Jan 27, 2026
WASM is missing in the multiplatform server sample Open

enhancement P3 ready for work samples

Difficulty 5/5 Over a week Newbie friendliness 35/100

modelcontextprotocol/kotlin-sdk#456 · Opened Dec 8, 2025

modelcontextprotocol/kotlin-sdk

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