Error loading config.toml: invalid type: sequence, expected a string in `mcp_servers.perplexity.env.env_vars`

What version of Codex is running?

codex-cli 0.66.0

What subscription do you have?

ChatGPT Plus

Which model were you using?

gpt-5.1-codex-max

What platform is your computer?

Microsoft Windows NT 10.0.19045.0 x64

What issue are you seeing?

I followed this guide to setup my Perplexity MCP: https://github.com/openai/codex/blob/main/docs/config.md#stdio

My ~/.codex/config.toml file:

[mcp_servers.perplexity]
command = "npx"
args = ["-y", "@perplexity-ai/mcp-server"]

[mcp_servers.perplexity.env]
env_vars = [ "PERPLEXITY_API_KEY" ]

When run codex, it will produce:

Error loading config.toml: invalid type: sequence, expected a string
in `mcp_servers.perplexity.env.env_vars`

I believe this is a bug from Codex CLI.

What steps can reproduce the bug?

1. codex mcp add perplexity -- npx -y '@perplexity-ai/mcp-server'
2. Configure ~/.codex/config.toml add env_vars to it
3. Run codex

What is the expected behavior?

This is either document wrong or Codex CLI implementation wrong.

Additional information

<img width="994" height="113" alt="Image" src="https://github.com/user-attachments/assets/35cd3fa8-d04b-4384-9f39-37acdc6b0b60" />