> ## Documentation Index > Fetch the complete documentation index at: https://docs.conduit.ai/llms.txt > Use this file to discover all available pages before exploring further. # List Custom Tool Runtimes > Returns the supported runtimes (Python, JavaScript) with the entrypoint signature, required return shape, starter template, built-in modules, and auto-installable packages for each. Read this before authoring tool code. ## OpenAPI ````yaml GET /v1/custom-tools/runtimes openapi: 3.0.0 info: title: Conduit API version: 1.0.0 description: Public API for Conduit. servers: - url: https://api.conduit.ai description: Production security: [] tags: - name: meta description: Discovery and API metadata endpoints. - name: agents description: >- V2 chat agent configuration, including instructions, skills, triggers, and automation behavior. - name: contacts description: >- Contact profile and contact-scoped related resources such as tickets and calls. - name: workspaces description: Workspaces accessible to the current API token. - name: escalations description: >- Chat escalations that require operator review, including message, proposed response, and disposition context when available. - name: conversations description: >- Canonical message threads. Use these endpoints to list threads, inspect conversation state, read transcripts, and send replies. - name: tickets description: >- Operational queue items tied to conversations, including ticket-scoped transcripts and replies. - name: calls description: Phone call records, transcripts, summaries, and recordings when available. - name: reservations description: >- PMS reservations synced from the workspace's integrations (Hostaway, Guesty, Airbnb, etc.), including guest identity, payment status, and stay dates. - name: appointments description: >- Scheduled appointments (bookings) backed by the Conduit booking service. Exposes allocation context and the upstream booking-service `external_id`. - name: helpdesk_tickets description: >- Helpdesk tickets mirrored from external helpdesk integrations (Zendesk, Pylon, Plain), including requester identity and upstream metadata. - name: kb description: >- Knowledge base search and node management. Nodes represent knowledge base entries (files or directories), chunks are the indexed retrieval units used by search. - name: skills description: >- Workspace agent skills that can be attached to V2 chat agents. Sidebar/global-assistant skills are intentionally excluded. - name: custom_tools description: >- Custom code tools: user-authored Python/JavaScript functions executed in a sandbox when an agent calls them. Includes a runtimes endpoint describing the entrypoint signature, return shape, and available dependencies per language. paths: /v1/custom-tools/runtimes: get: tags: - custom_tools summary: List custom tool runtimes description: >- Returns the supported custom tool runtimes (Python, JavaScript) with the exact entrypoint signature, required return shape, starter template, built-in modules, and auto-installable third-party packages for each. Read this before authoring `code` for create/update. operationId: listCustomToolRuntimes responses: '200': description: Supported custom tool runtimes content: application/json: schema: type: object properties: data: type: array items: type: object properties: language: type: string display_name: type: string file_extension: type: string package_manager: type: string entrypoint_signature: type: string return_contract: type: string starter_template: type: string builtin_modules: type: array items: type: string available_packages: type: array items: type: string required: - language - display_name - file_extension - package_manager - entrypoint_signature - return_contract - starter_template - builtin_modules - available_packages required: - data description: >- Supported custom tool runtimes, with the entrypoint signature, return contract, and available dependencies per language. example: data: - language: python display_name: Python file_extension: py package_manager: pip entrypoint_signature: def main(**params) -> dict return_contract: >- Return a dict containing a string `message` key. Optionally include `rawData` for structured data the agent can read. Example: `return {"message": "Found 3 results", "rawData": {...}}`. starter_template: |- def main(**params): result = "Hello from custom tool!" return {"message": result, "rawData": {"any": "additional data"}} builtin_modules: - json - math - datetime - re - urllib available_packages: - httpx - numpy - pandas - requests - language: javascript display_name: JavaScript file_extension: js package_manager: bun entrypoint_signature: async function main(params) -> object return_contract: >- Return an object containing a string `message` key. Optionally include `rawData` for structured data the agent can read. Example: `return { message: 'Found 3 results', rawData: {...} }`. starter_template: |- async function main(params) { const result = "Hello from custom tool!"; return { message: result, rawData: { any: "additional data" } }; } builtin_modules: - fs - path - crypto - https available_packages: [] '401': description: Unauthorized content: application/json: schema: type: object properties: error: type: string required: - error description: Standard error response. example: error: Invalid workspace id '429': description: Rate limit exceeded content: application/json: schema: type: object properties: error: type: string required: - error description: Standard error response. example: error: Invalid workspace id security: - bearerAuth: [] components: securitySchemes: bearerAuth: type: http scheme: bearer bearerFormat: API Token description: >- Conduit API token. Use `Authorization: Bearer `. Read/write endpoints require a token with write access. ````