JustCall MCP Server

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# JustCall MCP Server

The JustCall [Model Context Protocol (MCP)](https://modelcontextprotocol.com/) Server lets Large Language Models (LLMs) and AI agents make real-world voice calls and send SMS directly through JustCall’s APIs — securely, contextually, and programmatically.

It provides a function-calling interface for conversational AI systems, enabling:

- 📞 AI-powered calling: Let your LLM initiate, manage, or transcribe calls using JustCall.
- 💬 Smart messaging: Allow your AI agent to send or respond to SMS within conversations.
- ⚙️ Seamless integration: Use the MCP standard to connect JustCall’s telephony capabilities with any LLM runtime or orchestration framework.

In short: It gives your LLMs a voice and a phone number — turning chatbots into truly conversational agents.

## Claude Desktop Setup

1. Open `Claude Desktop` and press `CMD + ,` to go to `Settings`.
2. Click on the `Connectors` tab.
3. Click on the `Add Custom Connector` button.
4. Add name as `JustCall` and Remote Server Url as `https://mcp.justcall.host/mcp`.
5. Now on `JustCall` from the Connectors list click on `Connect` button for JustCall.
6. It will open a JustCall page requesting API key and secret.
7. Get your JustCall API Key & Secret from the JustCall dashboard (<https://app.justcall.io/app/developersApiCredentials>).
8. Enter the API key and Secret and press Continue, it should redirect back you to Claude.

## Claude Web - https://claude.ai

1. Open connectors url in your Browser - <https://claude.ai/settings/connectors>.
2. Click on the `Connectors` tab.
3. Click on the `Add Custom Connector` button.
4. Add name as `JustCall` and Remote Server Url as `https://mcp.justcall.host/mcp`.
5. Now on `JustCall` from the Connectors list click on `Connect` button for JustCall.
6. It will open a JustCall page requesting API key and secret.
7. Get your JustCall API Key & Secret from the JustCall dashboard (<https://app.justcall.io/app/developersApiCredentials>).
8. Enter the API key and Secret and press Continue, it should redirect back you to Claude.

## Chat GPT (Only available on Plus, Pro, Business and Enterprise)

1. Open connectors url in your Browser - <https://chatgpt.com/#settings/Connectors>.
2. Click on the `Apps & Connectors` tab.
3. Ensure developer mode is enabled in advanced settings
3. Click on the `Create` button.
4. Add name as `JustCall` and MCP Server Url as `https://mcp.justcall.host/mcp`. You can skip other fields.
5. Now on `JustCall` from the Connectors list click on `Connect` button for JustCall.
6. It will open a JustCall page requesting API key and secret.
7. Get your JustCall API Key & Secret from the JustCall dashboard (<https://app.justcall.io/app/developersApiCredentials>).
8. Enter the API key and Secret and press Continue, it should redirect back you to Chat GPT.

## Remote MCP

To connect to JustCall's MCP server remotely:

### Streamable HTTP (Recommended)

The default and recommended way to connect is via Streamable HTTP Transport:

- Connect to `https://mcp.justcall.host/mcp` from any MCP client using Streamable HTTP Transport
- Include your JustCall API key as a bearer token in the request headers
- Example header: `Authorization: Bearer <JUSTCALL_API_KEY>:<JUSTCALL_API_SECRET>`

## Authentication & Security

The JustCall MCP Server implements OAuth2 authentication for secure access to all endpoints.

### OAuth2 Configuration

The server supports OAuth2 authorization with the following features:

- **Authorization Endpoint**: OAuth2 authorization server metadata is available at `/.well-known/oauth-authorization-server`
- **Grant Type**: Authorization code flow with PKCE (Proof Key for Code Exchange)
- **Code Challenge Method**: S256 (SHA-256)
- **Token Authentication**: All MCP and SSE endpoints require Bearer token authentication

### Protected Endpoints

The following endpoints require valid Bearer token authentication:

- `/mcp` - Main MCP endpoint
- `/sse` - Server-Sent Events endpoint
- `/sse/message` - SSE message endpoint

### Authentication Header Format

Include your JustCall API credentials as a Bearer token:

```
Authorization: Bearer <JWT_TOKEN_BY_OAUTH>
Authorization: Bearer <JUSTCALL_API_KEY>:<JUSTCALL_API_SECRET>
```

### Public Endpoints

The following endpoints are publicly accessible:

- `/health` - Health check endpoint (returns 200 OK)
- `/.well-known/oauth-authorization-server` - OAuth2 authorization server metadata

### API Usage & Rate Limits

This MCP server uses the JustCall Developer API. All API requests are subject to the rate limits associated with your JustCall API key. Please refer to your [JustCall API credentials configuration](https://app.justcall.io/app/developersApiCredentials).

## Available Tools

The JustCall MCP Server provides 66 tools organized into the following categories:

### JustCall API Tools

#### 📞 Calls (6 tools)

- **list_calls** - Lists all JustCall calls with various filtering options
- **get_call** - Get a specific JustCall call by ID
-