Settings validation fails when unrelated env vars are present (e.g., OPENAI_API_KEY)

[daviskay75]

Description

Running docling-mcp-server fails with ValidationError: Extra inputs are not permitted
when environment variables like OPENAI_API_KEY are set.

Reproduction

export OPENAI_API_KEY=sk-...
uvx --from docling-mcp docling-mcp-server --transport stdio

Error

ValidationError: 1 validation error for Settings
openai_api_key
  Extra inputs are not permitted [type=extra_forbidden]

Root Cause

docling_mcp/settings/conversion.py uses pydantic_settings.BaseSettings without
an env_prefix, causing it to read ALL environment variables.

Suggested Fix

Add env_prefix in the Settings model config:

class Settings(BaseSettings):
    model_config = SettingsConfigDict(env_prefix="DOCLING_")
    # or
    model_config = SettingsConfigDict(extra="ignore")

Workaround

env -u OPENAI_API_KEY uvx --from docling-mcp docling-mcp-server --transport stdio

[bx-mm]

+1. Can't get the MCP working in any project where a .env file is present. I've worked around this issue by using a different command in my config file from the one that the README recommends. It changes to a different directory (one without an .env file) and runs the command from there. Ugly as hell though, this should really be looked at.

"docling": {
  "command": "bash",
  "args": [
    "-c",
    "cd ~ && uvx --from=docling-mcp docling-mcp-server --transport stdio"
  ]
}