Browser Agent MCP

Instructions

Implementation Reference

• src/executor.ts:378-402 (handler)

  The handler function for 'browser_fill' tool. It waits for the CSS selector to appear, fills the input field with the specified value using Playwright's page.fill(), and returns a success message or error.

  async function handleBrowserFill(page: Page, args: any): Promise<{ toolResult: CallToolResult }> {
    try {
      await page.waitForSelector(args.selector);
      await page.fill(args.selector, args.value);
      return {
        toolResult: {
          content: [{
            type: "text",
            text: `Filled ${args.selector} with: ${args.value}`,
          }],
          isError: false,
        },
      };
    } catch (error) {
      return {
        toolResult: {
          content: [{
            type: "text",
            text: `Fill operation failed on ${args.selector}: ${(error as Error).message}`,
          }],
          isError: true,
        },
      };
    }
  }

• src/tools.ts:84-95 (registration)

  Registration of the 'browser_fill' tool in the registerTools() function, including name, description, and input schema.

  {
    name: "browser_fill",
    description: "Fill a form input with text",
    inputSchema: {
      type: "object",
      properties: {
        selector: { type: "string", description: "CSS selector for input field" },
        value: { type: "string", description: "Text to enter in the field" }
      },
      required: ["selector", "value"]
    }
  },

• src/tools.ts:87-94 (schema)

  Input schema for the 'browser_fill' tool defining the required selector (CSS selector for input) and value (text to enter).

  inputSchema: {
    type: "object",
    properties: {
      selector: { type: "string", description: "CSS selector for input field" },
      value: { type: "string", description: "Text to enter in the field" }
    },
    required: ["selector", "value"]
  }

• src/executor.ts:197-198 (registration)

  Dispatch/registration case in the executeToolCall switch statement that calls the handleBrowserFill handler for 'browser_fill'.

  case "browser_fill":
    return await handleBrowserFill(activePage!, args);

• src/tools.ts:7-7 (registration)

  'browser_fill' included in BROWSER_TOOLS constant array, used to identify browser tools in executor.

  "browser_fill",