#!/usr/bin/env node
import { Server } from "@modelcontextprotocol/sdk/server/index.js";
import { StdioServerTransport } from "@modelcontextprotocol/sdk/server/stdio.js";
import {
CallToolRequestSchema,
ListToolsRequestSchema,
Tool,
} from "@modelcontextprotocol/sdk/types.js";
// Fixed chalk import for ESM
import chalk from 'chalk';
interface ThoughtData {
thought: string;
thoughtNumber: number;
totalThoughts: number;
isRevision?: boolean;
revisesThought?: number;
branchFromThought?: number;
branchId?: string;
needsMoreThoughts?: boolean;
nextThoughtNeeded: boolean;
}
class SequentialThinkingServer {
private thoughtHistory: ThoughtData[] = [];
private branches: Record<string, ThoughtData[]> = {};
private disableThoughtLogging: boolean;
constructor() {
this.disableThoughtLogging = (process.env.DISABLE_THOUGHT_LOGGING || "").toLowerCase() === "true";
}
private validateThoughtData(input: unknown): ThoughtData {
const data = input as Record<string, unknown>;
if (!data.thought || typeof data.thought !== 'string') {
throw new Error('Invalid thought: must be a string');
}
if (!data.thoughtNumber || typeof data.thoughtNumber !== 'number') {
throw new Error('Invalid thoughtNumber: must be a number');
}
if (!data.totalThoughts || typeof data.totalThoughts !== 'number') {
throw new Error('Invalid totalThoughts: must be a number');
}
if (typeof data.nextThoughtNeeded !== 'boolean') {
throw new Error('Invalid nextThoughtNeeded: must be a boolean');
}
return {
thought: data.thought,
thoughtNumber: data.thoughtNumber,
totalThoughts: data.totalThoughts,
nextThoughtNeeded: data.nextThoughtNeeded,
isRevision: data.isRevision as boolean | undefined,
revisesThought: data.revisesThought as number | undefined,
branchFromThought: data.branchFromThought as number | undefined,
branchId: data.branchId as string | undefined,
needsMoreThoughts: data.needsMoreThoughts as boolean | undefined,
};
}
private formatThought(thoughtData: ThoughtData): string {
const { thoughtNumber, totalThoughts, thought, isRevision, revisesThought, branchFromThought, branchId } = thoughtData;
let prefix = '';
let context = '';
if (isRevision) {
prefix = chalk.yellow('🔄 Revision');
context = ` (revising thought ${revisesThought})`;
} else if (branchFromThought) {
prefix = chalk.green('🌿 Branch');
context = ` (from thought ${branchFromThought}, ID: ${branchId})`;
} else {
prefix = chalk.blue('💭 Thought');
context = '';
}
const header = `${prefix} ${thoughtNumber}/${totalThoughts}${context}`;
const border = '─'.repeat(Math.max(header.length, thought.length) + 4);
return `
┌${border}┐
│ ${header} │
├${border}┤
│ ${thought.padEnd(border.length - 2)} │
└${border}┘`;
}
public processThought(input: unknown): { content: Array<{ type: string; text: string }>; isError?: boolean } {
try {
const validatedInput = this.validateThoughtData(input);
if (validatedInput.thoughtNumber > validatedInput.totalThoughts) {
validatedInput.totalThoughts = validatedInput.thoughtNumber;
}
this.thoughtHistory.push(validatedInput);
if (validatedInput.branchFromThought && validatedInput.branchId) {
if (!this.branches[validatedInput.branchId]) {
this.branches[validatedInput.branchId] = [];
}
this.branches[validatedInput.branchId].push(validatedInput);
}
if (!this.disableThoughtLogging) {
const formattedThought = this.formatThought(validatedInput);
console.error(formattedThought);
}
return {
content: [{
type: "text",
text: JSON.stringify({
thoughtNumber: validatedInput.thoughtNumber,
totalThoughts: validatedInput.totalThoughts,
nextThoughtNeeded: validatedInput.nextThoughtNeeded,
branches: Object.keys(this.branches),
thoughtHistoryLength: this.thoughtHistory.length
}, null, 2)
}]
};
} catch (error) {
return {
content: [{
type: "text",
text: JSON.stringify({
error: error instanceof Error ? error.message : String(error),
status: 'failed'
}, null, 2)
}],
isError: true
};
}
}
}
const SEQUENTIAL_THINKING_TOOL: Tool = {
name: "sequentialthinking",
description: `A detailed tool for DEEP, EXTENSIVE, and dynamic problem-solving through extended thinking.
This tool is designed for MAXIMUM DEPTH research and analysis with no artificial limits.
Each thought can build on, question, or revise previous insights as understanding deepens.
IMPORTANT: For deep research tasks, you should:
- Use 50+ thoughts minimum for complex problems, 100+ for deep research
- Take time to explore multiple angles and perspectives
- Question assumptions repeatedly throughout the process
- Revise and refine understanding as you progress
- Branch into alternative approaches when valuable
- Generate multiple hypotheses and verify each thoroughly
- Go as deep as needed - there is no maximum limit
When to use this tool:
- Breaking down complex problems into steps
- Planning and design with room for revision
- Analysis that might need course correction
- Problems where the full scope might not be clear initially
- Problems that require a multi-step solution
- Tasks that need to maintain context over multiple steps
- Situations where irrelevant information needs to be filtered out
- Deep research requiring extensive exploration
- Multi-hypothesis generation and verification
- Comprehensive analysis across multiple dimensions
Key features:
- You can adjust total_thoughts up or down as you progress
- You can question or revise previous thoughts
- You can add more thoughts even after reaching what seemed like the end
- You can express uncertainty and explore alternative approaches
- Not every thought needs to build linearly - you can branch or backtrack
- Generates a solution hypothesis
- Verifies the hypothesis based on the Chain of Thought steps
- Repeats the process until satisfied
- Provides a correct answer
Parameters explained:
- thought: Your current thinking step, which can include:
* Regular analytical steps
* Revisions of previous thoughts
* Questions about previous decisions
* Realizations about needing more analysis
* Changes in approach
* Hypothesis generation
* Hypothesis verification
- next_thought_needed: True if you need more thinking, even if at what seemed like the end
- thought_number: Current number in sequence (can go beyond initial total if needed)
- total_thoughts: Current estimate of thoughts needed (can be adjusted up/down)
- is_revision: A boolean indicating if this thought revises previous thinking
- revises_thought: If is_revision is true, which thought number is being reconsidered
- branch_from_thought: If branching, which thought number is the branching point
- branch_id: Identifier for the current branch (if any)
- needs_more_thoughts: If reaching end but realizing more thoughts needed
You should:
1. Start with an initial estimate of needed thoughts, but be ready to adjust UPWARD frequently
2. Feel free to question or revise previous thoughts extensively
3. Don't hesitate to add more thoughts if needed, even at the "end" - research has no artificial limits
4. Express uncertainty when present and explore it deeply
5. Mark thoughts that revise previous thinking or branch into new paths
6. Ignore information that is irrelevant to the current step
7. Generate MULTIPLE solution hypotheses when appropriate, not just one
8. Verify each hypothesis thoroughly based on the Chain of Thought steps
9. Repeat the hypothesis-verification cycle multiple times for robustness
10. Explore edge cases, counterexamples, and alternative interpretations
11. For deep research: aim for 100+ thoughts, exploring breadth AND depth
12. Use branching extensively to explore alternative paths in parallel
13. Perform multiple revision passes to refine understanding
14. Only set next_thought_needed to false when truly done with COMPREHENSIVE analysis
15. Provide a single, well-researched, thoroughly verified answer as the final output`,
inputSchema: {
type: "object",
properties: {
thought: {
type: "string",
description: "Your current thinking step"
},
nextThoughtNeeded: {
type: "boolean",
description: "Whether another thought step is needed"
},
thoughtNumber: {
type: "integer",
description: "Current thought number (numeric value, e.g., 1, 2, 3)",
minimum: 1
},
totalThoughts: {
type: "integer",
description: "Estimated total thoughts needed (numeric value, e.g., 5, 10)",
minimum: 1
},
isRevision: {
type: "boolean",
description: "Whether this revises previous thinking"
},
revisesThought: {
type: "integer",
description: "Which thought is being reconsidered",
minimum: 1
},
branchFromThought: {
type: "integer",
description: "Branching point thought number",
minimum: 1
},
branchId: {
type: "string",
description: "Branch identifier"
},
needsMoreThoughts: {
type: "boolean",
description: "If more thoughts are needed"
}
},
required: ["thought", "nextThoughtNeeded", "thoughtNumber", "totalThoughts"]
}
};
const server = new Server(
{
name: "sequential-thinking-server",
version: "0.2.0",
},
{
capabilities: {
tools: {},
},
}
);
const thinkingServer = new SequentialThinkingServer();
server.setRequestHandler(ListToolsRequestSchema, async () => ({
tools: [SEQUENTIAL_THINKING_TOOL],
}));
server.setRequestHandler(CallToolRequestSchema, async (request) => {
if (request.params.name === "sequentialthinking") {
return thinkingServer.processThought(request.params.arguments);
}
return {
content: [{
type: "text",
text: `Unknown tool: ${request.params.name}`
}],
isError: true
};
});
async function runServer() {
const transport = new StdioServerTransport();
await server.connect(transport);
console.error("Sequential Thinking MCP Server running on stdio");
}
runServer().catch((error) => {
console.error("Fatal error running server:", error);
process.exit(1);
});
