MCP Client

Overview

MCP (Model Context Protocol) is an open protocol for establishing standardized communication between large language model (LLM) applications and external data sources and tools. Apidog has a built-in MCP Client that supports debugging and testing MCP Servers.

MCP Servers provide three main features, all of which are supported for debugging by the Apidog MCP Client:

Tools: Executable server-side functions

Prompts: Predefined prompt templates

Resources: Data resources provided by the server

Two transport methods are supported:

STDIO: Communication via standard input/output, suitable for local processes

HTTP: Communication via Streamable HTTP, suitable for remote servers

Create MCP Client

Create a new endpoint in an HTTP project and select MCP.

Connect to MCP Server

Enter Server Address

Apidog supports multiple ways to input MCP Server connection information:

Direct Command or URL Input

When pasting a terminal command, the protocol automatically switches to STDIO:

When pasting a URL, the protocol automatically switches to HTTP:

https://learn.microsoft.com/api/mcp

Paste Configuration File

Apidog supports pasting MCP Server configuration files directly and will automatically parse and populate the relevant information.

MCP Servers File Example:

{
  "mcpServers": {
    "Everything Server": {
      "command": "npx",
      "args": ["-y", "@modelcontextprotocol/server-everything"],
      "env": {}
    }
  }
}

MCP Server Entry Example:

{
  "type": "streamable-http",
  "url": "https://learn.microsoft.com/api/mcp"
}

After pasting the configuration file, Apidog will automatically extract the server name, address, environment variables, and other information. If the configuration file contains multiple servers, the first one will be used.

Establish Connection

Click the Connect button to initiate the connection.

STDIO Connection

Since local command execution is required, Apidog will display a security confirmation dialog. After confirmation, it will start the local process and establish the connection.

HTTP Connection

Send a connection request directly to the specified URL.

For MCP Servers with OAuth 2.0 authentication, Apidog will automatically retrieve authentication configuration and display the authentication window

Other authentication methods (API Key, Bearer Token, Basic Auth, etc.) can also be manually configured in the Auth tab

After a successful connection, the directory tree will display the list of Tools, Prompts, and Resources provided by the server.

Debugging Features

Tools

Tools are executable functions provided by the server. After selecting a Tool, you can configure parameters via form or JSON editor.

After configuring the parameters, click Run to execute. Results will be displayed in the response area.

Prompts

Prompts are predefined prompt templates. After selecting a Prompt, configure parameters (if any) and click Run to get the generated prompt.

Resources

Resources are data resources provided by the server. After selecting a Resource, click Run to retrieve the resource content.

Configuration Options

Environment

Available only for STDIO mode. Used to configure environment variables when starting the MCP Server process.

Example:

Key	Value
ACCESS_TOKEN	your-token-here
NODE_ENV	production

Auth

Available only for HTTP mode. Supports multiple authentication methods:

API Key

Bearer Token

JWT Bearer

Basic Auth

Digest Auth

OAuth 2.0

For MCP Servers that support OAuth 2.0, Apidog can automatically retrieve and populate authentication configuration.

Headers

Available only for HTTP mode. Used to configure custom HTTP request headers.

View Response

The response area is divided into two tabs:

Response: Displays messages related to user operations (connect/disconnect events, requests/responses)

Notifications: Displays messages actively sent by the server (notifications, tool list updates, etc.)

Click on a message to view details including message type, content, timestamp, etc.

You can switch to "With Envelope" mode to view the complete JSON-RPC format (including envelope).

Variable Support

Variables {{variable_name}} are supported in the following locations:

Server address or command

Environment variable values

Request headers

Authentication information

Parameter values

Configured MCP clients can be saved to the project for subsequent use and team collaboration.

Note: The MCP directory tree (Tools, Prompts, Resources list) is stored locally only and refreshes automatically on each connection.

FAQ

STDIO connection fails with "command not found" error

Ensure the required runtime (such as Node.js) is installed and check that the command path is correct.

HTTP connection returns 401 error

Apidog will automatically attempt to retrieve OAuth 2.0 configuration. If it fails, manually configure authentication information in the Auth tab.

Connection successful but directory tree is empty

Check that the server configuration is correct and view the Notifications tab to confirm whether the server has returned the tool list.

Parameter type mismatch

When using form mode, Apidog will automatically validate parameter types. In JSON editor mode, be careful not to add quotes around numbers and use true/false for boolean values.

Overview#

Create MCP Client#

Connect to MCP Server#

Enter Server Address#

Establish Connection#

Debugging Features#

Tools#

Prompts#

Resources#

Configuration Options#

Environment#

Auth#

Headers#

View Response#

Variable Support#

Save and Share#

FAQ#

STDIO connection fails with "command not found" error#

HTTP connection returns 401 error#

Connection successful but directory tree is empty#

Parameter type mismatch#