Add to ~/.codex/config.toml.

Add the top-level feature flag (if not already set) plus the server block:

# Top level — enables streamable-HTTP MCP servers
experimental_use_rmcp_client = true

[mcp_servers.bankbridge]
url = "https://bankbridge.money/api/mcp"
bearer_token_env_var = "BANKBRIDGE_API_KEY"

The file may not exist yet — create it. The feature flag must be at the top level, not inside the [mcp_servers.bankbridge] block.

export BANKBRIDGE_API_KEY="bbk_your_api_key_here"

Grab a real key from your dashboard. Add the export to your ~/.zshrc or ~/.bashrc so it persists. Using an env var (rather than inlining the token inconfig.toml) means you can rotate keys without editing TOML.

Start Codex, then in any session:

how much did I spend this week?

If Codex reports zero tools loaded, double-check that experimental_use_rmcp_client = true is at the top level of config.toml— that’s the most common mistake.