Manifold Markets MCP Server

Instructions

Implementation Reference

• src/index.ts:684-722 (handler)

  The handler function for the 'sell_shares' tool. It validates input using SellSharesSchema, checks for API key, makes a POST request to Manifold Markets API endpoint /v0/market/{marketId}/sell to sell shares, handles errors, and returns the result as text content.

  case 'sell_shares': {
    const params = SellSharesSchema.parse(args);
    const apiKey = process.env.MANIFOLD_API_KEY;
    if (!apiKey) {
      throw new McpError(
        ErrorCode.InternalError,
        'MANIFOLD_API_KEY environment variable is required'
      );
    }
  
    const response = await fetch(`${API_BASE}/v0/market/${params.marketId}/sell`, {
      method: 'POST',
      headers: {
        'Content-Type': 'application/json',
        Authorization: `Key ${apiKey}`,
      },
      body: JSON.stringify({
        outcome: params.outcome,
        shares: params.shares,
      }),
    });
  
    if (!response.ok) {
      throw new McpError(
        ErrorCode.InternalError,
        `Manifold API error: ${response.statusText}`
      );
    }
  
    const result = await response.json();
    return {
      content: [
        {
          type: 'text',
          text: JSON.stringify(result, null, 2),
        },
      ],
    };
  }

• src/index.ts:77-81 (schema)

  Zod schema for validating input parameters to the sell_shares tool: marketId (required string), outcome (optional YES/NO), shares (optional number).

  const SellSharesSchema = z.object({
    marketId: z.string(),
    outcome: z.enum(['YES', 'NO']).optional(),
    shares: z.number().optional(),
  });

• src/index.ts:277-289 (registration)

  Tool registration in the ListTools handler, defining the name, description, and JSON inputSchema for sell_shares.

  {
    name: 'sell_shares',
    description: 'Sell shares in a market',
    inputSchema: {
      type: 'object',
      properties: {
        marketId: { type: 'string', description: 'Market ID' },
        outcome: { type: 'string', enum: ['YES', 'NO'], description: 'Which type of shares to sell (defaults to what you have)' },
        shares: { type: 'number', description: 'How many shares to sell (defaults to all)' },
      },
      required: ['marketId'],
    },
  },