How to declare environment variable schemas for MCP servers in skills.
Environment Variable Schema
Skills that include MCP servers often need configuration values like API keys, connection strings, or endpoints. The config.env section in shipables.json declares these requirements so the CLI can prompt users during installation.
Declaration format
{
"config": {
"env": [
{
"name": "DATABASE_URL",
"description": "PostgreSQL connection string",
"required": true,
"secret": true,
"default": ""
},
{
"name": "LOG_LEVEL",
"description": "Logging verbosity (debug, info, warn, error)",
"required": false,
"secret": false,
"default": "info"
}
]
}
}
Fields
| Field | Type | Required | Default | Description |
|---|---|---|---|---|
name | string | Yes | — | Environment variable name. Convention: UPPER_SNAKE_CASE. |
description | string | Yes | — | Human-readable description shown to the user during install. |
required | boolean | No | false | Whether the variable must be provided. |
secret | boolean | No | false | If true, user input is hidden (password-style entry). |