Concurrent Browser MCP

Instructions

Implementation Reference

• src/tools.ts:747-767 (handler)

  The core handler function that executes the browser_fill tool logic using Playwright's page.fill method to fill a form field with the given value.

  private async fill(instanceId: string, selector: string, value: string, timeout: number): Promise<ToolResult> {
    const instance = this.browserManager.getInstance(instanceId);
    if (!instance) {
      return { success: false, error: `Instance ${instanceId} not found` };
    }
  
    try {
      await instance.page.fill(selector, value, { timeout });
      return {
        success: true,
        data: { selector, value, filled: true },
        instanceId
      };
    } catch (error) {
      return {
        success: false,
        error: `Fill failed: ${error instanceof Error ? error.message : error}`,
        instanceId
      };
    }
  }

• src/tools.ts:240-262 (schema)

  Input schema definition for the browser_fill tool, specifying parameters like instanceId, selector, value, and timeout.

  inputSchema: {
    type: 'object',
    properties: {
      instanceId: {
        type: 'string',
        description: 'Instance ID'
      },
      selector: {
        type: 'string',
        description: 'Element selector',
      },
      value: {
        type: 'string',
        description: 'Value to fill',
      },
      timeout: {
        type: 'number',
        description: 'Timeout in milliseconds',
        default: 30000
      }
    },
    required: ['instanceId', 'selector', 'value']
  }

• src/tools.ts:237-263 (registration)

  Tool registration in the getTools() method, defining name, description, and input schema for browser_fill.

  {
    name: 'browser_fill',
    description: 'Fill a form field',
    inputSchema: {
      type: 'object',
      properties: {
        instanceId: {
          type: 'string',
          description: 'Instance ID'
        },
        selector: {
          type: 'string',
          description: 'Element selector',
        },
        value: {
          type: 'string',
          description: 'Value to fill',
        },
        timeout: {
          type: 'number',
          description: 'Timeout in milliseconds',
          default: 30000
        }
      },
      required: ['instanceId', 'selector', 'value']
    }
  },

• src/tools.ts:547-549 (registration)

  Dispatch/registration in the executeTools switch statement that routes browser_fill calls to the fill handler method.

  case 'browser_fill':
    return await this.fill(args.instanceId, args.selector, args.value, args.timeout || 30000);