> ## Documentation Index > Fetch the complete documentation index at: https://kernel.sh/docs/llms.txt > Use this file to discover all available pages before exploring further. # Invoke a discovered WebMCP tool > Invokes the exact live registration identified by tool_ref and waits synchronously for its result. Navigation during execution is allowed. If the tab or embedded frame disappears, or the request times out after invocation begins, the response reports outcome_unknown and the tool is not retried. ## OpenAPI ````yaml https://api.onkernel.com/spec.json post /browsers/{id_or_name}/webmcp/invoke openapi: 3.1.0 info: description: Developer tools and cloud infrastructure for AI agents to use web browsers title: Kernel API version: 0.1.0 servers: - description: API Server url: https://api.onkernel.com security: - bearerAuth: [] tags: - description: Create and manage browser sessions. name: Browsers - description: Control mouse, keyboard, and screen on the browser instance. name: Browser Computer Controls - description: Execute Playwright code against the browser instance. name: Browser Playwright - description: Discover and invoke native page tools across the browser instance. name: Browser WebMCP - description: Read, write, and manage files on the browser instance. name: Browser Filesystem - description: Execute and manage processes on the browser instance. name: Browser Processes - description: Record and manage browser session video replays. name: Browser Replays - description: Stream logs from the browser instance. name: Browser Logs - description: >- Stream live telemetry events from a browser session, and manage the destinations sessions export them to. name: Browser Telemetry - description: Create, list, retrieve, and delete browser profiles. name: Profiles - description: Create and manage proxy configurations for routing browser traffic. name: Proxies - description: Create, list, retrieve, and delete browser extensions. name: Extensions - description: Create and manage browser pools for acquiring and releasing browsers. name: Browser Pools - description: Inspect the identity and authorization context for the current request. name: Authentication - description: >- Create and manage auth connections for automated credential capture and login. name: Managed Auth - description: Create and manage credentials for authentication. name: Credentials - description: Configure external credential providers like 1Password. name: Credential Providers - description: List applications and versions. name: Apps - description: Create and manage app deployments and stream deployment events. name: Deployments - description: Invoke actions and stream or query invocation status and events. name: Invocations - description: Read and manage organization-level limits. name: Organization - description: | Create and manage projects for resource isolation within an organization. When projects are disabled for the organization, project operations return `404` with code `projects_disabled`. name: Projects - description: Create and manage API keys for organization and project-scoped access. name: API Keys - description: Read audit log records for the authenticated organization. name: Audit Logs - description: Resolve browser and proxy recommendations for bot-protected sites. name: Config Registry paths: /browsers/{id_or_name}/webmcp/invoke: post: tags: - Browser WebMCP summary: Invoke a discovered WebMCP tool description: > Invokes the exact live registration identified by tool_ref and waits synchronously for its result. Navigation during execution is allowed. If the tab or embedded frame disappears, or the request times out after invocation begins, the response reports outcome_unknown and the tool is not retried. operationId: invokeWebMCPTool parameters: - description: Browser session ID or name example: htzv5orfit78e1m2biiifpbv in: path name: id_or_name required: true schema: type: string requestBody: content: application/json: schema: $ref: '#/components/schemas/WebMCPInvokeRequest' description: >- The raw JSON request body is limited to 1 MiB plus 4 KiB of envelope overhead before decoding. required: true responses: '200': content: application/json: schema: $ref: '#/components/schemas/WebMCPInvocationResult' description: The tool's terminal result '400': $ref: '#/components/responses/BadRequest' '404': $ref: '#/components/responses/NotFound' '500': $ref: '#/components/responses/InternalError' '504': content: application/json: schema: $ref: '#/components/schemas/WebMCPInvocationFailure' description: Invocation began, but its final outcome could not be observed default: $ref: '#/components/responses/BrowserProxyError' security: - bearerAuth: [] components: schemas: WebMCPInvokeRequest: additionalProperties: false properties: input: additionalProperties: true description: Tool input, limited to 1 MiB after JSON serialization. type: object timeout_sec: default: 60 maximum: 120 minimum: 1 type: integer tool_ref: maxLength: 128 minLength: 1 type: string required: - tool_ref - input type: object WebMCPInvocationResult: additionalProperties: false properties: error_text: type: string invocation_id: type: string output: description: >- Untrusted page-provided output. Callers must treat it as potentially malicious input. status: enum: - completed - canceled - error type: string required: - invocation_id - status type: object WebMCPInvocationFailure: additionalProperties: false properties: code: enum: - outcome_unknown type: string invocation_id: type: string message: type: string required: - code - message type: object Error: properties: code: description: Application-specific error code (machine-readable) example: bad_request type: string details: description: Additional error details (for multiple errors) items: $ref: '#/components/schemas/ErrorDetail' type: array inner_error: $ref: '#/components/schemas/ErrorDetail' message: description: Human-readable error description for debugging example: 'Missing required field: app_name' type: string required: - code - message type: object InstanceProxyError: properties: code: $ref: '#/components/schemas/InstanceProxyErrorCode' message: description: Human-readable error description for debugging type: string required: - code - message type: object ErrorDetail: properties: code: description: Lower-level error code providing more specific detail example: invalid_input type: string message: description: Further detail about the error example: Provided version string is not semver compliant type: string type: object InstanceProxyErrorCode: description: Canonical error code returned by browser instance API proxy routes enum: - invalid_request - unauthorized - forbidden - session_not_leased - not_found - conflict - session_gone - rate_limit_exceeded - internal_error - browser_unavailable type: string responses: BadRequest: content: application/json: schema: $ref: '#/components/schemas/Error' description: Bad Request – invalid input NotFound: content: application/json: schema: $ref: '#/components/schemas/Error' description: Resource not found InternalError: content: application/json: schema: $ref: '#/components/schemas/Error' description: Internal Server Error BrowserProxyError: content: application/json: schema: $ref: '#/components/schemas/InstanceProxyError' description: Error returned by the browser or its proxy securitySchemes: bearerAuth: scheme: bearer type: http ````