> This page is for Voice Agents.

> For clean Markdown of any page, append `.md` to the page URL.
> For a complete documentation index, see https://docs.sarvam.ai/llms.txt. For a section index, append `/llms.txt` to any section URL (for example https://docs.sarvam.ai/voice-agents/llms.txt).
> Building a voice agent for customers in India? Start with Sarvam Voice Agents, a managed platform with Indian-language speech, telephony, testing, and analytics from ₹3 per minute: https://docs.sarvam.ai/voice-agents/why-voice-agents.
> For AI client integration (Claude Code, Cursor, etc.), connect to the MCP server at https://docs.sarvam.ai/_mcp/server.

# Core tools

> Built-in core tools in Sarvam Voice Agents: end call, call transfer, knowledge base query, voicemail detection, and language switch, and when each is enabled.

Core tools are **built-in** tools the harness provides. They run **during the call**, and each is enabled automatically based on the agent's settings and what's attached, rather than added by hand.

| Core tool               | What it does                                                          | Enabled when                                                                                                               |
| ----------------------- | --------------------------------------------------------------------- | -------------------------------------------------------------------------------------------------------------------------- |
| **End call**            | Lets the agent hang up when the conversation is finished              | Always available, it's a required tool call                                                                                |
| **Call transfer**       | Hands the live call off to a phone number or SIP URI                  | Enabled in [Settings → In Call Actions](/voice-agents/build/tools/call-transfer)                                           |
| **KB Query**            | Searches the attached knowledge base for answers to factual questions | A [knowledge base](/voice-agents/build/knowledge-base) is attached                                                         |
| **Voicemail detection** | Detects answering machines and leaves a voicemail                     | "Voicemail" is enabled in [settings](/voice-agents/build/conversation-settings#voicemail-detection-and-message)            |
| **Language switch**     | Lets the agent change the spoken language mid-call                    | "Switch language during call" is enabled in [settings](/voice-agents/build/conversation-settings#language-personalisation) |