MCP Vapi Caller
Server Configuration
Describes the environment variables required to run the server.
| Name | Required | Description | Default |
|---|---|---|---|
| VAPI_API_KEY | Yes | Vapi API key | |
| MCP_TRANSPORT | No | stdio or streamable-http | stdio |
| VAPI_VOICE_ID | Yes | ElevenLabs voice ID | |
| VAPI_LLM_MODEL | No | LLM model (validated against Vapi's Anthropic list) | claude-sonnet-4-6 |
| DEFAULT_LANGUAGE | No | Default BCP-47 call language | fr |
| VAPI_VOICE_MODEL | No | ElevenLabs TTS model | eleven_flash_v2_5 |
| VAPI_VOICE_SPEED | No | Speech speed | 1.0 |
| VAPI_LLM_PROVIDER | No | Vapi LLM provider | anthropic |
| DEFAULT_CALLER_NAME | No | Who the agent calls on behalf of | |
| VAPI_VOICE_PROVIDER | No | TTS provider | 11labs |
| VAPI_PHONE_NUMBER_ID | Yes | Vapi phone number ID (UUID) | |
| VAPI_VOICE_STABILITY | No | Voice stability (0.0–1.0) | 0.5 |
| VAPI_VOICE_SIMILARITY_BOOST | No | Voice similarity boost (0.0–1.0) | 0.75 |
Instructions
Guidance the server publishes about itself, which clients place ahead of the tool catalog so the model reads it before choosing anything.
This server publishes no instructions, or was last inspected before Glama recorded them.
Capabilities
Features and capabilities supported by this server
Protocol revision2025-11-25
| Capability | Details |
|---|---|
| tools | {
"listChanged": false
} |
| prompts | {
"listChanged": false
} |
| resources | {
"subscribe": false,
"listChanged": false
} |
| experimental | {} |
Tools
Functions exposed to the LLM to take actions
| Name | Description |
|---|---|
| make_callA | Make an outbound phone call with an AI voice agent via Vapi. The voice agent will call the given phone number, follow your script, and extract structured data from the conversation. After initiating the call, use get_call_result() to retrieve the outcome. WORKFLOW:
REQUIRED PARAMETERS:
RECOMMENDED PARAMETERS:
OPTIONAL PARAMETERS:
TIPS FOR GOOD CALLS:
Args: phone_number: Phone number in E.164 format (e.g. "+33142000000") call_goal: One sentence describing what the call should achieve call_script: Detailed behavioral instructions for the voice agent language: BCP-47 language code (default: "fr") caller_name: Who the agent calls on behalf of caller_context: Additional identity context for the voice agent first_message: Opening line when the call connects structured_data_schema: JSON string of a JSON Schema for data extraction structured_data_prompt: Instructions for the extraction model end_call_phrases: Comma-separated end-call phrases voice_id: ElevenLabs voice ID override customer_name: Name of the person/business being called system_prompt_override: Full system prompt (replaces auto-generated one) |
| get_call_resultA | Check the outcome of a call initiated by make_call(). Returns the call status, transcript, AI-generated summary, success evaluation, structured extracted data, and recording URL. USAGE:
TYPICAL CALL DURATION: 1-3 minutes. Use wait_seconds=180 for most calls. RETURNED FIELDS (when call has ended):
If the call is still in progress, returns the current status without the analysis fields. Call again with wait_seconds to poll. Args: call_id: The call ID returned by make_call wait_seconds: If > 0, poll every 5s up to this duration waiting for the call to end. 0 means check once and return immediately. |
Prompts
Interactive templates invoked by user choice
| Name | Description |
|---|---|
No prompts | |
Resources
Contextual data attached and managed by the client
| Name | Description |
|---|---|
No resources | |
TDQS
Scored across 2 tools
The two tools have entirely distinct purposes: one initiates a call, the other retrieves its result. There is no overlap or ambiguity between them.
Both tools follow the verb_noun pattern: make_call and get_call_result. The naming is consistent and predictable.
With only two tools, the set feels thin but the scope is narrow. The two tools cover the primary workflow, though additional utilities (like cancelling a call) could be expected.
The core lifecycle of initiating a call and retrieving its result is well covered. A minor gap exists in lack of cancellation or management of calls, but agents can work around this by waiting for completion.