modelcontextprotocol/typescript-sdk

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The official TypeScript SDK for Model Context Protocol servers and clients

Stars: 13.4k
Forks: 2.2k
Open beginner issues: 25
Indexed issues: 300
Avg merge: 3d 15h
Merged PRs (30d): 4

Dominant language: TypeScript
License: No license data
Last GitHub push: Sep 16, 2026
Latest indexed: Sep 20, 2026
Contributing guide: Contributing guide
Code of conduct: Code of conduct
Beginner labels: good first issue help wanted

Beginner friendly Everything

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300 open issues indexed

Step-up authorization (403 insufficient_scope) dead-ends with SdkHttpError when a refresh_token is present Open

auth bug potentially close

Difficulty 3/5 1-2 days Newbie friendliness 62/100

modelcontextprotocol/typescript-sdk#2255 · 4 comments · Opened Jun 5, 2026
MCP tool calls timeout after 60 seconds for long-running requests Open

enhancement potentially close question

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

modelcontextprotocol/typescript-sdk#2250 · 4 comments · Opened Jun 3, 2026
Invalid Request frames silently dropped with no error response — client hangs waiting for id that never resolves Open

bug fix proposed P2 ready for work

Difficulty 3/5 1-2 days Newbie friendliness 68/100

modelcontextprotocol/typescript-sdk#2247 · 6 comments · Opened Jun 2, 2026
Published package omits `src/` but `dist/**/*.js.map` references it, breaking source-map consumers Open

bug P2 ready for work

Difficulty 3/5 1-2 days Newbie friendliness 55/100

modelcontextprotocol/typescript-sdk#2233 · 4 comments · 1 reaction · Opened Jun 1, 2026
sendToolListChanged drops notifications on stateless Streamable HTTP transports (missing relatedRequestId) Open

bug fix proposed P2 ready for work

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

modelcontextprotocol/typescript-sdk#2232 · 7 comments · Opened Jun 1, 2026
Implement SEP-2663: Tasks Extension Open

enhancement needs decision P2 v2

modelcontextprotocol/typescript-sdk#2189 · 2 comments · 1 assignee · Opened May 29, 2026
Session Close Notification for Stateful Connections (MCP Clients) Open

bug enhancement needs decision P2

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

modelcontextprotocol/typescript-sdk#2175 · 2 comments · 1 reaction · Opened May 29, 2026
`UriTemplate.match()` returns `null` for multi-variable path expressions like `{userId,format}` Open

bug fix proposed P2 ready for work

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

modelcontextprotocol/typescript-sdk#2166 · 3 comments · Opened May 28, 2026
AbortSignal cancellation throws `SdkErrorCode.RequestTimeout` instead of a distinct abort error Open

bug fix proposed good first issue P2

Difficulty 3/5 1-2 days Newbie friendliness 75/100

modelcontextprotocol/typescript-sdk#2165 · 4 comments · Opened May 28, 2026
invalid argument should throw protocol error, rather than tool execution error Open

bug potentially close

Difficulty 3/5 1-2 days Newbie friendliness 63/100

modelcontextprotocol/typescript-sdk#2162 · 2 comments · 2 reactions · Opened May 28, 2026
Claude.AI hangs with 408 timeout when MCP tool response JSON contains U+2028 (LINE SEPARATOR) or U+2029 (PARAGRAPH SEPARATOR) Open

bug fix proposed P2 ready for work

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

modelcontextprotocol/typescript-sdk#2155 · 4 comments · Opened May 25, 2026
closeSSEStream() breaks request-scoped SSE resumability for terminal responses Open

potentially close v2

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

modelcontextprotocol/typescript-sdk#2151 · 1 comment · Opened May 24, 2026
tools/list returns empty inputSchema for ZodEffects-wrapped schemas (Zod .superRefine / .refine / .transform / .pipe) Open

bug fix proposed P2 ready for work

Difficulty 4/5 3-5 days Newbie friendliness 65/100

modelcontextprotocol/typescript-sdk#2145 · 5 comments · Opened May 22, 2026
OAuth AS metadata discovery crashes on 200 OK + non-JSON response instead of falling back to OIDC Open

auth bug fix proposed P2 ready for work

Difficulty 3/5 1-2 days Newbie friendliness 55/100

modelcontextprotocol/typescript-sdk#2126 · 2 comments · Opened May 20, 2026
Streamable HTTP server accepts mismatched `MCP-Protocol-Version` header and body `protocolVersion` on `initialize` Open

bug fix proposed P2 ready for work

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

modelcontextprotocol/typescript-sdk#2108 · 5 comments · Opened May 16, 2026
Is there a way to pass request-scoped context to tool handlers via HTTP headers without modifying the tool schema? Open

potentially close question

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

modelcontextprotocol/typescript-sdk#2101 · 1 comment · 2 reactions · Opened May 15, 2026
Tool inputSchema generation emits $ref for reused Zod instances · breaks strict MCP clients (kimi) Open

bug

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

modelcontextprotocol/typescript-sdk#2100 · 3 comments · Opened May 15, 2026
StreamableHTTPClientTransport: 2-retry SSE reconnect ceiling + silent-success after exhaustion Open

bug P2 ready for work

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

modelcontextprotocol/typescript-sdk#2098 · 2 comments · Opened May 15, 2026
Stateless mode: per-request McpServer+Protocol allocation causes memory leak at scale Open

enhancement needs decision P3

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

modelcontextprotocol/typescript-sdk#2090 · 1 comment · 1 reaction · Opened May 14, 2026
[SEP-1613 regression] tools/list still emits draft-07 in 1.29.0 — `target` option missing from mcp.js `toJsonSchemaCompat` calls Open

bug fix proposed P1 ready for work

Difficulty 2/5 1-3 hours Newbie friendliness 78/100

modelcontextprotocol/typescript-sdk#2084 · 6 comments · 1 reaction · Opened May 14, 2026
Type inconsistency: StreamableHTTPServerTransport.onclose widens Transport interface contract under exactOptionalPropertyTypes Open

potentially close

Difficulty 2/5 1-3 hours Newbie friendliness 68/100

modelcontextprotocol/typescript-sdk#2083 · 2 comments · Opened May 13, 2026
`resetTimeoutOnProgress` on low-level `request()` only works when `onprogress` is explicitly provided Open

bug fix proposed P2 ready for work

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

modelcontextprotocol/typescript-sdk#2076 · 3 comments · Opened May 12, 2026
`registerPrompt()` silently drops `icons` from PromptDefinition config Open

potentially close

Difficulty 2/5 1-3 hours Newbie friendliness 70/100

modelcontextprotocol/typescript-sdk#2054 · 1 comment · Opened May 12, 2026
High-severity CVEs via pnpm audit Open

bug P2 ready for work

Difficulty 3/5 1-2 days Newbie friendliness 52/100

modelcontextprotocol/typescript-sdk#2048 · 1 comment · 1 reaction · Opened May 11, 2026
Security: Transitive dependencies with known vulnerabilities in @modelcontextprotocol/sdk@1.29.0 Open

potentially close

Difficulty 2/5 1-3 hours Newbie friendliness 68/100

modelcontextprotocol/typescript-sdk#2042 · 1 comment · 1 reaction · Opened May 10, 2026
DEFAULT_INHERITED_ENV_VARS Open

bug fix proposed P2 ready for work

Difficulty 2/5 1-3 hours Newbie friendliness 88/100

modelcontextprotocol/typescript-sdk#2037 · 3 comments · 1 reaction · Opened May 9, 2026
Bump hono and fast-uri to versions covering published GHSA advisories Open

enhancement P2 ready for work

Difficulty 3/5 1-2 days Newbie friendliness 55/100

modelcontextprotocol/typescript-sdk#2036 · 7 comments · Opened May 9, 2026
Feature request: allow customizing `taskId` in `InMemoryTaskStore` Open

enhancement needs decision P3

Difficulty 4/5 3-5 days Newbie friendliness 52/100

modelcontextprotocol/typescript-sdk#2032 · 1 comment · 1 reaction · Opened May 8, 2026
Completables should pass through authInfo and signal Open

auth enhancement needs decision P3

Difficulty 4/5 3-5 days Newbie friendliness 52/100

modelcontextprotocol/typescript-sdk#2029 · Opened May 7, 2026
Proposal: Move examples to a separate repository to avoid dependency-related vulnerabilities Open

enhancement needs decision P3

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

modelcontextprotocol/typescript-sdk#2025 · 2 reactions · Opened May 6, 2026
StdioClientTransport.close() does not kill the process tree, leaving orphan processes Open

bug fix proposed P2 ready for work

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

modelcontextprotocol/typescript-sdk#2023 · 2 comments · Opened May 6, 2026
TaskStore interface should pass through authInfo and signal Open

auth enhancement needs decision P3

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

modelcontextprotocol/typescript-sdk#2020 · Opened May 5, 2026
handleAutomaticTaskPolling ignores AbortSignal; cancelled requests poll indefinitely Open

potentially close

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

modelcontextprotocol/typescript-sdk#2018 · 1 comment · Opened May 5, 2026
tools/call with null arguments returns -32603 (InternalError) instead of being accepted Open

bug fix proposed P2 ready for work

Difficulty 3/5 1-2 days Newbie friendliness 66/100

modelcontextprotocol/typescript-sdk#2012 · 1 comment · Opened May 2, 2026
zod listed in both dependencies and peerDependencies causes duplicate installs and TS type-incompatibility Open

bug fix proposed P2 ready for work

Difficulty 2/5 1-3 hours Newbie friendliness 68/100

modelcontextprotocol/typescript-sdk#2011 · 1 comment · 2 reactions · Opened May 2, 2026
Bug: StdioServerTransport doesn't handle stdin close/end — causes zombie process accumulation Open

bug fix proposed P1 ready for work

Difficulty 2/5 1-3 hours Newbie friendliness 82/100

modelcontextprotocol/typescript-sdk#2002 · 8 comments · 2 reactions · Opened May 1, 2026
Stateless StreamableHTTPServerTransport: non-initialize requests return 500 with empty body when transport is reused (regression vs 1.24.3) Open

bug fix proposed P2 ready for work

Difficulty 4/5 3-5 days Newbie friendliness 55/100

modelcontextprotocol/typescript-sdk#1994 · 1 comment · Opened Apr 30, 2026
RegisteredTool.update() crashes with ZodObject inputSchema (passthrough schemas) Open

bug fix proposed good first issue P2

Difficulty 2/5 1-3 hours Newbie friendliness 76/100

modelcontextprotocol/typescript-sdk#1960 · 2 comments · Opened Apr 25, 2026
Bug: `_handleSseStream` retains reader lock on stream close, leaking ~50MB per reconnection Open

potentially close

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

modelcontextprotocol/typescript-sdk#1959 · 2 comments · Opened Apr 25, 2026
SEP-1303: Input validation errors should return Tool Execution Errors, not Protocol Errors Open

potentially close

Difficulty 3/5 1-2 days Newbie friendliness 64/100

modelcontextprotocol/typescript-sdk#1956 · 3 comments · Opened Apr 24, 2026
adaptOAuthProvider returns expired tokens without checking expiry, breaking long-running StreamableHTTP connections Open

auth bug P2 ready for work

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

modelcontextprotocol/typescript-sdk#1954 · 2 comments · Opened Apr 24, 2026
OAuth discovery does not fall back to well-known URI when 401 carries a non-Bearer WWW-Authenticate (e.g. Negotiate) Open

auth bug needs repro

Difficulty 2/5 1-3 hours Newbie friendliness 76/100

modelcontextprotocol/typescript-sdk#1946 · 3 comments · Opened Apr 22, 2026
StreamableHTTPServerTransport rejects JSON-only Accept with 406 even when enableJsonResponse: true Open

bug fix proposed P2 ready for work

Difficulty 3/5 1-2 days Newbie friendliness 68/100

modelcontextprotocol/typescript-sdk#1944 · 3 comments · 1 reaction · Opened Apr 22, 2026
deps: include hono@4.12.14 in the next dependabot bump (GHSA-458j-xx4x-4375) Open

enhancement needs decision P3

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

modelcontextprotocol/typescript-sdk#1941 · Opened Apr 21, 2026
McpServer: add tool lifecycle hooks (beforeToolCall, afterToolCall) Open

enhancement needs decision P3

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

modelcontextprotocol/typescript-sdk#1928 · 2 comments · 2 reactions · Opened Apr 19, 2026
Optional install of HTTP/SSE transport deps (express, hono) for stdio-only servers Open

enhancement needs decision P3

Difficulty 3/5 1-2 days Newbie friendliness 55/100

modelcontextprotocol/typescript-sdk#1924 · 2 comments · Opened Apr 17, 2026
authExtensions docs say custom claims override reserved JWT claims, but implementation keeps reserved claims authoritative Open

bug documentation fix proposed P3 ready for work

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

modelcontextprotocol/typescript-sdk#1914 · 4 comments · Opened Apr 16, 2026
Client transport: HTTP 429 responses are not retried with Retry-After Open

enhancement needs decision P3

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

modelcontextprotocol/typescript-sdk#1892 · Opened Apr 15, 2026
Feature: add idle timeout to SSE stream reader in StreamableHTTPClientTransport Open

enhancement needs decision P3

Difficulty 3/5 1-2 days Newbie friendliness 55/100

modelcontextprotocol/typescript-sdk#1883 · 1 comment · Opened Apr 12, 2026
Public API for multi-node session rehydration (e.g. transport.adoptSession(id)) Open

enhancement needs decision P3

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

modelcontextprotocol/typescript-sdk#1882 · 1 comment · Opened Apr 12, 2026

modelcontextprotocol/typescript-sdk

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