From c8e9150272adeff0a067073a07e74699c82cd183 Mon Sep 17 00:00:00 2001 From: Amir Fathi Date: Mon, 17 Aug 2026 18:27:17 +0000 Subject: [PATCH 1/2] fix(sequentialthinking): restore nextThoughtNeeded in the advertised inputSchema required array commit 1cdf806d (#3533) wrapped nextThoughtNeeded in a z.preprocess-based coercedBoolean to fix a real footgun (string "false" coercing to true). zod's toJSONSchema(..., { io: "input" }) treats a z.preprocess()-wrapped field's input type as unknown, so it silently drops that field from the emitted required array, even though it carries no .optional(). A client that builds its call arguments from the advertised schema then omits nextThoughtNeeded and gets a -32602 Invalid params from the runtime validator, which still requires it. Rebuild coercedBoolean as a transform on an explicit z.union([z.boolean(), z.string()]) instead of z.preprocess. The union gives toJSONSchema a concrete input type to report, so nextThoughtNeeded stays in required, while parse behavior (including the case-insensitive string coercion #3533 added) is unchanged. Fixes #4651 --- src/sequentialthinking/index.ts | 16 ++++++++-------- 1 file changed, 8 insertions(+), 8 deletions(-) diff --git a/src/sequentialthinking/index.ts b/src/sequentialthinking/index.ts index 217845bb3d..5872830c48 100644 --- a/src/sequentialthinking/index.ts +++ b/src/sequentialthinking/index.ts @@ -5,15 +5,15 @@ import { StdioServerTransport } from "@modelcontextprotocol/sdk/server/stdio.js" import { z } from "zod"; import { SequentialThinkingServer } from './lib.js'; -/** Safe boolean coercion that correctly handles string "false" */ -const coercedBoolean = z.preprocess((val) => { +/** Safe boolean coercion that correctly handles string "false". A union+transform, + * not z.preprocess (whose input type is `unknown`), so toJSONSchema keeps this required. */ +const coercedBoolean = z.union([z.boolean(), z.string()]).transform((val, ctx) => { if (typeof val === "boolean") return val; - if (typeof val === "string") { - if (val.toLowerCase() === "true") return true; - if (val.toLowerCase() === "false") return false; - } - return val; -}, z.boolean()); + if (val.toLowerCase() === "true") return true; + if (val.toLowerCase() === "false") return false; + ctx.addIssue({ code: "custom", message: `Expected boolean or "true"/"false" string, received "${val}"` }); + return z.NEVER; +}); const server = new McpServer({ name: "sequential-thinking-server", From bfd926871d8bb0303bc6be4d5d7ea0df2af8186c Mon Sep 17 00:00:00 2001 From: olaservo Date: Fri, 28 Aug 2026 10:05:50 -0700 Subject: [PATCH 2/2] test(sequentialthinking): pin nextThoughtNeeded in required and string coercion Runs against the built server so it checks the schema the SDK emits. Skips when dist/ is absent, matching server-version.test.ts. Co-Authored-By: Claude Fable 5 Claude-Session: https://claude.ai/code/session_018Wo28CHPXyM3DHoLWvKnCK --- .../__tests__/input-schema.test.ts | 66 +++++++++++++++++++ 1 file changed, 66 insertions(+) create mode 100644 src/sequentialthinking/__tests__/input-schema.test.ts diff --git a/src/sequentialthinking/__tests__/input-schema.test.ts b/src/sequentialthinking/__tests__/input-schema.test.ts new file mode 100644 index 0000000000..4ff7be663c --- /dev/null +++ b/src/sequentialthinking/__tests__/input-schema.test.ts @@ -0,0 +1,66 @@ +import { describe, it, expect, beforeAll, afterAll } from 'vitest'; +import { existsSync } from 'node:fs'; +import path from 'node:path'; +import { fileURLToPath } from 'node:url'; +import { Client } from '@modelcontextprotocol/sdk/client/index.js'; +import { StdioClientTransport } from '@modelcontextprotocol/sdk/client/stdio.js'; + +const packageRoot = path.join(path.dirname(fileURLToPath(import.meta.url)), '..'); +const distIndexPath = path.join(packageRoot, 'dist', 'index.js'); + +// Regression coverage for #4651: nextThoughtNeeded must stay in the advertised +// `required` array, and string coercion must keep accepting "True"/"FALSE" +// while rejecting anything else. Runs against the built server so it checks +// the schema the SDK actually emits, not the zod object. +describe.skipIf(!existsSync(distIndexPath))('sequentialthinking input schema', () => { + let client: Client; + + beforeAll(async () => { + const transport = new StdioClientTransport({ + command: process.execPath, + args: [distIndexPath], + cwd: packageRoot, + stderr: 'pipe', + }); + client = new Client({ name: 'input-schema-test', version: '0.0.0' }); + await client.connect(transport); + }); + + afterAll(async () => { + await client?.close(); + }); + + it('advertises nextThoughtNeeded as required', async () => { + const { tools } = await client.listTools(); + const tool = tools.find(t => t.name === 'sequentialthinking'); + expect(tool).toBeDefined(); + expect(tool!.inputSchema.required).toEqual( + expect.arrayContaining(['thought', 'nextThoughtNeeded', 'thoughtNumber', 'totalThoughts']) + ); + }); + + it('rejects a call that omits nextThoughtNeeded', async () => { + const result = await client.callTool({ + name: 'sequentialthinking', + arguments: { thought: 't', thoughtNumber: 1, totalThoughts: 1 }, + }); + expect(result.isError).toBe(true); + expect(JSON.stringify(result.content)).toMatch(/nextThoughtNeeded/); + }); + + it.each(['True', 'FALSE', 'true', 'false'])('accepts the string %s', async (value) => { + const result = await client.callTool({ + name: 'sequentialthinking', + arguments: { thought: 't', nextThoughtNeeded: value, thoughtNumber: 1, totalThoughts: 1 }, + }); + expect(result.isError).toBeFalsy(); + }); + + it.each(['yes', '', '1'])('rejects the string %j', async (value) => { + const result = await client.callTool({ + name: 'sequentialthinking', + arguments: { thought: 't', nextThoughtNeeded: value, thoughtNumber: 1, totalThoughts: 1 }, + }); + expect(result.isError).toBe(true); + }); +});