create_sparkline

Instructions

Implementation Reference

• src/charts/sparkline.ts:10-71 (handler)

  The main handler function that executes the create_sparkline tool logic, generating ASCII sparklines with optional min/max labels, coloring, and titles.

  export function createSparkline(data: ChartData, options: SparklineOptions = {}): ChartResult {
    const { data: values, title, width = 40, color = 'white' } = data;
    const { showMinMax = true, fillChar } = options;
    
    if (values.length === 0) {
      throw new Error('Data array cannot be empty');
    }
  
    const minValue = Math.min(...values);
    const maxValue = Math.max(...values);
    const valueRange = maxValue - minValue;
    
    // Calculate sparkline width (reserve space for min/max if shown)
    const sparklineWidth = showMinMax ? width - 20 : width;
    
    let sparkline = '';
    
    // Generate sparkline using block characters
    if (fillChar) {
      // Use custom fill character
      for (let i = 0; i < Math.min(values.length, sparklineWidth); i++) {
        sparkline += fillChar;
      }
    } else {
      // Use gradient block characters
      const blocks = ASCII_CHARS.sparkBlocks;
      
      for (let i = 0; i < Math.min(values.length, sparklineWidth); i++) {
        const normalizedValue = valueRange === 0 ? 0.5 : normalize(values[i], minValue, maxValue);
        const blockIndex = Math.floor(normalizedValue * (blocks.length - 1));
        sparkline += blocks[blockIndex];
      }
    }
    
    // Add min/max values if requested
    if (showMinMax) {
      const minStr = minValue.toFixed(1);
      const maxStr = maxValue.toFixed(1);
      sparkline = `${minStr} ${sparkline} ${maxStr}`;
    }
    
    // Apply coloring
    if (color !== 'white') {
      sparkline = colorize(sparkline, color);
    }
    
    // Add title if provided
    let result = sparkline;
    if (title) {
      const titleLine = center(title, sparkline.length);
      result = titleLine + '\n' + sparkline;
    }
    
    return {
      chart: result,
      title,
      dimensions: { 
        width: sparkline.length, 
        height: title ? 2 : 1 
      }
    };
  }

• src/index.ts:377-384 (registration)

  Tool dispatch/registration in the CallToolRequestSchema handler's switch statement, calling the createSparkline implementation.

  case 'create_sparkline': {
    progress.nextStep('Generating sparkline');
    result = await withRequestTracking(
      () => Promise.resolve(createSparkline(chartData)),
      'create_sparkline'
    )();
    break;
  }

• src/index.ts:238-268 (schema)

  Input schema definition for the create_sparkline tool, listed in ListToolsRequestSchema response.

  name: 'create_sparkline',
  description: 'Generate compact ASCII sparklines for inline charts',
  inputSchema: {
    type: 'object',
    properties: {
      data: {
        type: 'array',
        items: { type: 'number' },
        description: 'Array of numeric values to plot'
      },
      title: {
        type: 'string',
        description: 'Optional sparkline title',
        optional: true
      },
      width: {
        type: 'number',
        description: 'Sparkline width (10-100, default: 40)',
        minimum: 10,
        maximum: 100,
        optional: true
      },
      color: {
        type: 'string',
        description: 'ANSI color name',
        optional: true
      }
    },
    required: ['data'],
    examples: getToolExamples('create_sparkline')
  }

• src/charts/sparkline.ts:5-8 (schema)

  Type definition for SparklineOptions used in the handler function.

  export interface SparklineOptions {
    showMinMax?: boolean;
    fillChar?: string;
  }

• src/utils/examples.ts:89-104 (helper)

  Example inputs for the create_sparkline tool.

  create_sparkline: {
    compact: {
      data: [1, 3, 2, 5, 4, 7, 6, 8],
      title: "Quick Trend"
    },
    metrics: {
      data: [23, 25, 22, 28, 30, 27, 31, 29, 33],
      title: "System Load",
      color: "red",
      width: 30
    },
    inline: {
      data: [100, 102, 98, 105, 110, 108, 112],
      width: 25
    }
  }