> ## Documentation Index > Fetch the complete documentation index at: https://docs.retellai.com/llms.txt > Use this file to discover all available pages before exploring further. # Get Test Case Definition > Get a test case definition by ID ## OpenAPI ````yaml openapi-final get /get-test-case-definition/{test_case_definition_id} openapi: 3.0.3 info: title: Retell SDK version: 3.0.0 contact: name: Retell Support url: https://www.retellai.com/ email: support@retellai.com license: name: Apache 2.0 url: https://www.apache.org/licenses/LICENSE-2.0.html servers: - url: https://api.retellai.com description: The production server. security: - api_key: [] paths: /get-test-case-definition/{test_case_definition_id}: get: description: Get a test case definition by ID operationId: getTestCaseDefinition parameters: - in: path name: test_case_definition_id schema: type: string required: true description: ID of the test case definition to retrieve responses: '200': description: Test case definition retrieved successfully content: application/json: schema: $ref: '#/components/schemas/TestCaseDefinition' '400': $ref: '#/components/responses/BadRequest' '401': $ref: '#/components/responses/Unauthorized' '404': $ref: '#/components/responses/NotFound' '429': $ref: '#/components/responses/TooManyRequests' '500': $ref: '#/components/responses/InternalServerError' x-codeSamples: - lang: JavaScript source: >- import Retell from 'retell-sdk'; const client = new Retell({ apiKey: process.env['RETELL_API_KEY'], // This is the default and can be omitted }); const testCaseDefinitionResponse = await client.tests.getTestCaseDefinition( 'test_case_definition_id', ); console.log(testCaseDefinitionResponse.test_case_definition_id); - lang: Python source: >- import os from retell import Retell client = Retell( api_key=os.environ.get("RETELL_API_KEY"), # This is the default and can be omitted ) test_case_definition_response = client.tests.get_test_case_definition( "test_case_definition_id", ) print(test_case_definition_response.test_case_definition_id) components: schemas: TestCaseDefinition: allOf: - $ref: '#/components/schemas/TestCaseDefinitionInput' - type: object required: - name - response_engine - metrics - user_prompt - dynamic_variables - tool_mocks - llm_model - test_case_definition_id - type - creation_timestamp - user_modified_timestamp properties: test_case_definition_id: type: string description: Unique identifier for the test case definition type: type: string enum: - simulation description: Type of test case definition creation_timestamp: type: integer description: >- Timestamp when the test case definition was created (milliseconds since epoch) user_modified_timestamp: type: integer description: >- Timestamp when the test case definition was last modified (milliseconds since epoch) TestCaseDefinitionInput: type: object properties: name: type: string description: Name of the test case definition response_engine: $ref: '#/components/schemas/RetellResponseEngine' description: >- Response engine to use for the test case. Custom LLM is not supported. user_prompt: type: string description: User prompt to simulate in the test case metrics: type: array items: type: string description: Array of metric names to evaluate dynamic_variables: type: object additionalProperties: type: string description: Dynamic variables to inject into the response engine tool_mocks: type: array items: $ref: '#/components/schemas/ToolMock' description: Mock tool calls for testing llm_model: $ref: '#/components/schemas/LLMModel' description: LLM model to use for simulation RetellResponseEngine: oneOf: - $ref: '#/components/schemas/ResponseEngineRetellLm' - $ref: '#/components/schemas/ResponseEngineConversationFlow' description: Response engine for test cases. Custom LLM is not supported. ToolMock: description: >- A fake response for one tool. During a simulation, when the LLM calls a tool whose name matches `tool_name` and whose arguments satisfy `input_match_rule`, the real tool is not run; `output` is returned to the LLM instead. This keeps runs deterministic and avoids calling live integrations. A tool call that matches no mock falls through to the real tool. type: object required: - tool_name - input_match_rule - output properties: tool_name: type: string description: >- The tool's function name, not the tool ID, i.e. the name the LLM uses when it calls the tool (for example `check_availability_cal`, `book_appointment_cal`, or the name you gave a custom function). input_match_rule: $ref: '#/components/schemas/ToolMockInputMatchRule' description: Decides which calls to this tool the mock applies to. output: type: string maxLength: 15000 description: >- The tool result fed back to the LLM in place of the real tool's output. Should be a JSON string, the same shape the real tool would return. result: type: boolean nullable: true description: >- For tool calls like transfer_call that require a boolean result. Optional for most tools. LLMModel: type: string enum: - gpt-4.1 - gpt-4.1-mini - gpt-4.1-nano - gpt-5 - gpt-5-mini - gpt-5-nano - gpt-5.1 - gpt-5.2 - gpt-5.4 - gpt-5.4-mini - gpt-5.4-nano - gpt-5.5 - claude-4.5-sonnet - claude-4.6-sonnet - claude-5-sonnet - claude-4.5-haiku - gemini-3.0-flash - gemini-3.1-flash-lite - gemini-3.5-flash description: Available LLM models for agents. ResponseEngineRetellLm: type: object required: - type - llm_id properties: type: type: string enum: - retell-llm description: type of the Response Engine. llm_id: type: string description: id of the Retell LLM Response Engine. version: type: number example: 0 description: Version of the Retell LLM Response Engine. nullable: true ResponseEngineConversationFlow: type: object required: - type - conversation_flow_id properties: type: type: string enum: - conversation-flow description: type of the Response Engine. conversation_flow_id: type: string description: ID of the Conversation Flow Response Engine. version: type: number example: 0 description: Version of the Conversation Flow Response Engine. nullable: true ToolMockInputMatchRule: description: >- Decides which calls to the tool this mock applies to, based on the arguments the LLM passes to the tool. oneOf: - type: object required: - type properties: type: type: string enum: - any description: >- Match every call to the tool, no matter what arguments were passed. Use this for a catch-all mock. - type: object required: - type - args properties: type: type: string enum: - partial_match description: >- Match only calls whose arguments contain the values listed in `args`. args: type: object description: >- Argument values the call must have to match. Only the fields you list here are checked, and each must equal the value in the actual call. Extra fields in the call are ignored, so this is a subset match. responses: BadRequest: description: Bad Request content: application/json: schema: type: object properties: status: type: string enum: - error message: type: string example: Invalid request format, please check API reference. Unauthorized: description: Unauthorized content: application/json: schema: type: object properties: status: type: string enum: - error message: type: string example: API key is missing or invalid. NotFound: description: Not Found content: application/json: schema: type: object properties: status: type: string enum: - error message: type: string example: The requested resource was not found. TooManyRequests: description: Too Many Requests content: application/json: schema: type: object properties: status: type: string enum: - error message: type: string example: Account rate limited, please throttle your requests. InternalServerError: description: Internal Server Error content: application/json: schema: type: object properties: status: type: string enum: - error message: type: string example: An unexpected server error occurred. securitySchemes: api_key: type: http scheme: bearer bearerFormat: string description: >- Authentication header containing API key (find it in dashboard). The format is "Bearer YOUR_API_KEY" ````