codex-mcp-config-format-matrix

codex-mcp-config-format-matrix is a skill for Claude Code, Codex from davidruzicka/mcp4openapi. It costs 36 tokens per session (551 once invoked), scanned A, original, MIT.

A rule guide for writing MCP (Model Context Protocol) connection settings for Codex, the coding agent. It covers the correct command-line and TOML formats for bearer tokens, custom headers, and environment variables.

In plain words
What is it for?
Use it when creating or reviewing Codex MCP server settings, including TOML profiles and command-line examples that connect to authenticated services.
Why use it?
It prevents configuration examples from using authentication formats that Codex does not support or interpret correctly. It also avoids repeating the same environment variable in multiple places.

Skill for Claude CodeCodex

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/davidruzicka/mcp4openapi/codex-mcp-config-format-matrix
Any agent
npx skills add davidruzicka/mcp4openapi --skill codex-mcp-config-format-matrix
Clone the repo
git clone --depth 1 https://github.com/davidruzicka/mcp4openapi

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for codex-mcp-config-format-matrix

README.md
[![agentmods](https://agentmods.dev/badge/skills/davidruzicka/mcp4openapi/codex-mcp-config-format-matrix.svg)](https://agentmods.dev/skills/davidruzicka/mcp4openapi/codex-mcp-config-format-matrix)
Your own site
<a href="https://agentmods.dev/skills/davidruzicka/mcp4openapi/codex-mcp-config-format-matrix"><img src="https://agentmods.dev/badge/skills/davidruzicka/mcp4openapi/codex-mcp-config-format-matrix.svg" alt="Measured on agentmods" height="20"></a>
Per session 36 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 551 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00036 $0.00551
Opus 5 $0.00018 $0.00275
Sonnet 5 $0.00007 $0.00110
Haiku 4.5 $0.00004 $0.00055

Measured 4d ago against content hash ff588d1a571d, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

codex-mcp-config-format-matrix scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 4d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

.claude/skills/codex-mcp-config-format-matrix/SKILL.md · 39 lines

How it starts

The opening of the file, as written. The whole thing — 39 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Goal

Generate correct Codex MCP snippets without mixing conventions from other clients.

When to Use

  • A task adds or edits Codex snippets in profile index pages.
  • A review checks Codex CLI or TOML examples.

Rules

  1. For Codex TOML in [mcp_servers.<name>] sections:
    • with bearer auth, use bearer_token_env_var = "<ENV_VAR_NAME>" - do not encode bearer auth in TOML as Authorization header values.
    • when bearer_token_env_var is set, do not duplicate the same variable in env_vars.
    • with custom header, use http_headers = { "Header-Name" = "value" }.
    • with custom header that uses environment variable as a value, use env_http_headers = { "Header-Name" = "<ENV_VAR_NAME>" }.
    • for environment variables mapping from host, use env_vars =["<ENV_VAR_NAME>", ...].
  2. For Codex CLI:
    • with bearer auth which uses defined environment variable as a token, use --bearer-token-env-var <ENV_VAR_NAME>.
    • don't generate CLI snippet other than OAuth or bearer auth - pure command line arguments doesn't support custom-header or query authentication types and also doesn't support environment variables mapping from host.
  3. env TOML snippets should be used to define environment variables:
    [mcp_servers.<server_name>.env]
    ENV_VAR_NAME = "value"
    
  4. Keep Codex snippets client-native:
  • TOML snippets use [mcp_servers.<name>].
  • CLI snippets use codex mcp add <mcp_server_name> --url "https://..." for HTTP streamable MCP servers and codex mcp add <mcp_server_name> -- npx -y mpc4openapi --profile <profile_name> ... for stdio MCP servers.
  1. Keep env placeholders aligned with the target format:
  • Codex TOML/CLI uses ${VAR} style values when variable interpolation is shown.

Validation Checklist

  • Bearer TOML contains bearer_token_env_var and no embedded bearer header.
  • Bearer TOML does not duplicate the bearer variable in env_vars.
  • Non-bearer custom headers in TOML are emitted via http_headers.
  • Snippet tests cover bearer and query/custom-header paths.

Read the full file on GitHub · 39 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 4d ago First seen · 39 lines · 36 tokens per session scan A ff588d1a571d

Subscribe to this mod's changes

codex-mcp-config-format-matrix is a skill published in the GitHub repository davidruzicka/mcp4openapi (0 stars, last pushed yesterday), licensed MIT. It adds 36 tokens to every session and 551 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

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