Use Dutyfinch MCP with OpenAI Codex CLI

US tariff API + MCP: HTS duty rates, Section 301 lists. Keys $19/mo; 50 free calls a day.

Remote MCP server (Streamable HTTP), nothing to install. Free: 50 free calls a day · Paid: Keys $19/mo

Set it up

Open ~/.codex/config.toml (create it if needed).
Add the [mcp_servers] table shown and save.
Start Codex; the server's tools are available to the agent.
Ask a question the tools can answer.

Add to ~/.codex/config.toml:

[mcp_servers.dutyfinch]
url = "https://dutyfinch.cybermaxtools.com/mcp?via=use-with-codex"

With a paid key:

[mcp_servers.dutyfinch]
url = "https://dutyfinch.cybermaxtools.com/mcp?via=use-with-codex"
env_http_headers = { "x-api-key" = "CYBERMAX_API_KEY" }

env_http_headers maps the header to an environment variable name, so the key stays in your environment.

Where it goes:

~/.codex/config.toml (or .codex/config.toml in a trusted project)

Config format checked 2026-10-09 against OpenAI Codex CLI's MCP documentation.

Tools you get

Endpoint checked 2026-10-09: https://dutyfinch.cybermaxtools.com/mcp answered an MCP initialize (protocol 2025-06-18) and tools/list with 4 tools, all marked read-only. No key was used and no tool was called.

Tool	What it does	Required inputs
`lookup_hts_code`	US tariff lookup for one HTS code (4, 6, 8 or 10 digits): description, general/special/column 2 duty rates, Section 301 China list status with the additional rate, exclusions, and the 2026 US–China reduction flag.	`code`
`search_hts`	Find US HTS codes from product words (e.g. "air fryer", "wooden toys") or a code prefix. Returns codes with description, general rate and Section 301 China summary.	`q`
`section301_lists`	All Section 301 China tariff headings (lists 1, 2, 3, 4A, 4B, 2024 increases, exclusions) with rates, dates and code counts.	none
`china_deal_status`	Status of the 2026 US–China tariff reduction list (pending / notice_published / published) and, with code, whether that HTS code is on it.	none

Test the endpoint from a terminal

This lists the tools without a key and without calling any of them:

curl -s https://dutyfinch.cybermaxtools.com/mcp \
  -H 'content-type: application/json' \
  -H 'accept: application/json, text/event-stream' \
  -d '{"jsonrpc":"2.0","id":1,"method":"tools/list"}'

If it does not work

Each server is its own [mcp_servers.<name>] table; keep the name to letters, digits, dashes and underscores.
For a fixed header value instead of an environment variable, Codex also documents http_headers.
The free tier has a daily limit (see the pricing line above); a paid key raises it.

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