HAL — Claude Code MCP server: API access and setup
HAL lets an AI client make HTTP requests and can create tools from an OpenAPI specification. Use it when an agent needs to call your project’s API.
claude mcp add hal -- npx -y hal-mcpWhat HAL does
HAL is an MCP server for HTTP calls. It supports GET, POST, PUT, PATCH, DELETE, OPTIONS, and HEAD requests, and can build API tools from an OpenAPI or Swagger specification. Provide that specification as a file or URL.
Set credentials in environment variables prefixed with HAL_SECRET_, then refer to them in requests with placeholders such as {secrets.api_key}. HAL inserts the values when making a request and redacts them from returned responses, headers, and error messages. The secrets must be configured in the server environment first.
URL allowlists and blocklists can limit which addresses the server may access. Set HAL_SWAGGER_FILE to load an API specification and HAL_API_BASE_URL to provide a base address. Start the server with npx -y hal-mcp.
What it helps with
- send HTTP requests to an API from an agent chat
- generate callable tools from an OpenAPI specification
- use an API key without exposing its value to the model
- restrict API access to selected URLs
Example prompts for the agent
- Fetch the project’s task list through its HTTP API.
- Build tools from the OpenAPI specification and call the profile endpoint.
- Call the API using
HAL_SECRET_API_KEYwithout revealing its value.
How to install HAL
Platform CLI
claude mcp add hal -- npx -y hal-mcpPlatform CLI
codex mcp add hal -- npx -y hal-mcpConfig file
{
"mcpServers": {
"hal": {
"command": "npx",
"args": [
"-y",
"hal-mcp"
]
}
}
}Config file
{
"servers": {
"hal": {
"type": "stdio",
"command": "npx",
"args": [
"-y",
"hal-mcp"
]
}
}
}Platform CLI
gemini mcp add hal npx -y hal-mcpStep by step, with commands for each platform: How to add an MCP server to Claude Code, Codex, Cursor, VS Code, Gemini CLI and more
Questions about HAL
How do I install HAL in Claude Code?
Run claude mcp add hal -- npx -y hal-mcp. This adds the HAL MCP server.
What does HAL do?
HAL lets an agent make HTTP requests to APIs. It can also create tools from OpenAPI or Swagger specifications.
How does HAL handle API secrets?
Set credentials in environment variables with the HAL_SECRET_ prefix, then reference them with placeholders such as {secrets.key}. HAL inserts the values for requests and redacts them from responses returned to the agent.
