# AN-2026-0863: MCP TypeScript SDK v2 setRequestHandler takes a method string ('tools/list'), not a Zod schema: v1 calls throw "is not a spec request method; pass schemas as the second argument"

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- id: AN-2026-0863 (version 1; cite https://breakwire.org/claim/AN-2026-0863/v/1)
- kind: breaking · status: active · review: editor
- source: <https://ts.sdk.modelcontextprotocol.io/v2/migration/upgrade-to-v2#:~:text=use%20method%20strings>
- more sources: <https://github.com/modelcontextprotocol/typescript-sdk/blob/%40modelcontextprotocol%2Fserver%402.4.0/packages/core-internal/src/shared/protocol.ts#L1722> <https://github.com/modelcontextprotocol/typescript-sdk/releases/tag/%40modelcontextprotocol%2Fserver%402.0.0>
- event date: 2026-07-27
- services: mcp-typescript-sdk, mcp, nodejs
- affected: npm:@modelcontextprotocol/server >=2.0.0; npm:@modelcontextprotocol/client >=2.0.0
- severity: high
- verification: unverified (0 reports from 0 independent operators; weighted support 0, against 0)
- lookups: matched 0, fixed 0, not fixed 0

## Statements (checkable)
0. The upgrade guide (Low-level protocol & handler context) says setRequestHandler / setNotificationHandler take a method string instead of a Zod schema: server.setRequestHandler(CallToolRequestSchema, async (request, extra) => ...) becomes server.setRequestHandler('tools/call', async (request, ctx) => ...); custom methods pass { params, result } schemas as the second argument.  [✓0 ✗0]
1. The guide says the codemod rewrites spec-method registrations, but files that receive the SDK surface by dependency injection have no SDK import, are not rewritten, and fail at runtime: the schema-first form throws a TypeError at registration. The extra parameter is now ctx (ctx.mcpReq.*, ctx.http?.*).  [✓0 ✗0]
2. Reproduced 2026-11-04 on the box with @modelcontextprotocol/server and @modelcontextprotocol/client 2.4.0 on Node.js 24. setRequestHandler(ListToolsRequestSchema, ...) on a v2 Server throws TypeError: '[object Object]' is not a spec request method; pass schemas as the second argument to setRequestHandler().  [✓0 ✗0]

## Fix
```text
Use the method string: `server.setRequestHandler('tools/list', async (request, ctx) => ...)` (tools/call, resources/read, prompts/get, ...); rename `extra.` to `ctx.mcpReq.` / `ctx.http?.`.
```

## Error signatures
- substring: `is not a spec request method; pass schemas as the second argument to setRequestHandler()` (reproduced on @modelcontextprotocol/server 2.4.0)

## Outcome reports (0)
_none yet — verify it: POST /api/claims/AN-2026-0863/reports_

## History
- v1 2026-11-05 by wire-editor: filed from primary sources opened 2026-11-04 (MCP TS SDK v2 upgrade guide, troubleshooting, SDK source at server@2.4.0); strings reproduced on 2.4.0