> ## Documentation Index > Fetch the complete documentation index at: https://docs.roark.ai/llms.txt > Use this file to discover all available pages before exploring further. # Set a tool fixture > Create-or-replace by scope: one fixture per tool project-wide, plus one per (tool, flow variant). Setting the same scope twice replaces the response, so CI can apply fixtures idempotently. During Roark test calls the tool guard answers with the fixture verbatim instead of generating a response; real callers are never affected. ## OpenAPI ````yaml /api-reference/openapi.documented.json post /v1/simulation/tool-fixture openapi: 3.1.0 info: title: Roark Analytics API description: >- The Roark Analytics API gives you access to the same API that powers the award winning Roark Analytics platform. version: 1.0.0 servers: - description: Production url: https://api.roark.ai security: - Bearer: [] tags: - name: Agent - name: Agent Endpoint - name: Call - name: Chat - name: Metric - name: Metric Policy - name: Metric Collection Job - name: Customer Flow - name: Customer Flow Edge Case - name: Simulation - name: Simulation Persona - name: Simulation Environment - name: Simulation Scenario - name: Simulation Run Plan - name: Simulation Template - name: Simulation Run Plan Job - name: Simulation Job - name: HTTP Request Definition - name: Webhook - name: Issue - name: Autoimprove - name: Agent Config - name: Knowledge Base - name: Config - name: CLI Auth - name: Call Analysis - name: Benchmark - name: Health paths: /v1/simulation/tool-fixture: post: tags: - Simulation summary: Set a tool fixture description: >- Create-or-replace by scope: one fixture per tool project-wide, plus one per (tool, flow variant). Setting the same scope twice replaces the response, so CI can apply fixtures idempotently. During Roark test calls the tool guard answers with the fixture verbatim instead of generating a response; real callers are never affected. operationId: postV1SimulationTool-fixture requestBody: content: application/json: schema: $ref: '#/components/schemas/UpsertSimulationToolFixtureRequest' responses: '200': description: The fixture as stored. content: application/json: schema: type: object properties: data: $ref: '#/components/schemas/SimulationToolFixture' required: - data '400': content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' description: Validation error example: type: validation code: invalid_parameter message: The request was invalid param: email description: Bad Request '401': content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' description: Authentication error example: type: authentication code: unauthorized message: Authentication required description: Unauthorized '403': content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' description: Permission error example: type: forbidden code: permission_denied message: You do not have permission to access this resource description: Forbidden '404': content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' description: Not found error example: type: not_found code: resource_not_found message: The requested resource could not be found description: The referenced flow variant does not exist in this project. '429': content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' description: Rate limit error example: type: rate_limit code: too_many_requests message: Rate limit exceeded description: Too Many Requests '500': content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' description: Server error example: type: internal code: internal_error message: Internal server error description: Internal Server Error x-codeSamples: - lang: JavaScript source: >- import Roark from '@roarkanalytics/sdk'; const client = new Roark({ bearerToken: process.env['ROARK_API_BEARER_TOKEN'], // This is the default and can be omitted }); const simulationToolFixture = await client.simulationToolFixture.create({ toolName: 'lookup_availability', }); console.log(simulationToolFixture.data); - lang: Python source: |- import os from roark_analytics import Roark client = Roark( bearer_token=os.environ.get("ROARK_API_BEARER_TOKEN"), # This is the default and can be omitted ) simulation_tool_fixture = client.simulation_tool_fixture.create( tool_name="lookup_availability", ) print(simulation_tool_fixture.data) components: schemas: UpsertSimulationToolFixtureRequest: type: object properties: toolName: type: string minLength: 1 maxLength: 200 description: The tool this fixture answers for. example: lookup_availability response: description: The exact JSON to return. example: slots: [] customerFlowVariantId: type: string format: uuid description: >- Pin the fixture to one flow variant (scenario). Omit for a project-wide fixture. A variant-pinned fixture beats the project-wide one. description: type: string maxLength: 1000 description: Why this fixture exists. example: Forces the no-availability branch enabled: type: boolean description: Defaults to true. required: - toolName SimulationToolFixture: type: object properties: id: type: string format: uuid toolName: type: string example: lookup_availability customerFlowVariantId: type: - string - 'null' format: uuid description: The flow variant this fixture is pinned to. Null = project-wide. response: description: The exact JSON the tool returns during Roark test calls. description: type: - string - 'null' description: Why this fixture exists. enabled: type: boolean createdAt: type: string description: ISO 8601. updatedAt: type: string description: ISO 8601. required: - id - toolName - customerFlowVariantId - description - enabled - createdAt - updatedAt description: >- A deterministic tool response for Roark test calls: where the scenario-aware model makes mocked tools plausible, a fixture makes one exact, so a simulation can force the branch under test. Never applies to real callers. ErrorResponse: type: object properties: type: type: string enum: - validation - authentication - forbidden - not_found - conflict - payment_required - rate_limit - internal description: The error type category examples: - validation - authentication code: type: string description: Machine-readable error code identifier examples: - invalid_parameter - missing_required_field - unauthorized message: type: string description: Human-readable error message examples: - The request was invalid - Authentication required param: type: string description: The parameter that caused the error (if applicable) examples: - email - user_id details: description: Additional error context information required: - type - code - message securitySchemes: Bearer: type: http scheme: bearer bearerFormat: JWT ````