api-config

Reference material for configuring an MCP server and its framework. It explains environment variables, defaults, priority rules, server-specific Zod validation, and delayed configuration parsing for Cloudflare Workers.

In plain words
What is it for?
Use it to define environment settings, choose which value takes precedence, validate application-specific configuration, and handle lazy parsing in Workers.
Why use it?
Configuration can come from several places, and mixing framework settings with an application's own settings can cause unexpected behavior.

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/cyanheads/reference-data-mcp-server/api-config
Any agent
npx skills add cyanheads/reference-data-mcp-server --skill api-config
Clone the repo
git clone --depth 1 https://github.com/cyanheads/reference-data-mcp-server

Made for: Claude Code, Codex.

Per session 43 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 5,288 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin 95% copy Near-identical to another mod 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 $0.00043 $0.05288
Opus 5 $0.00022 $0.02644
Sonnet 5 $0.00009 $0.01058
Haiku 4.5 $0.00004 $0.00529

Measured 2d ago against content hash 44f4d41d9fa6, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

api-config 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 2d 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.

Origin

This is a copy

95% identical to api-config — 4 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

skills/api-config/SKILL.md · 289 lines

How it starts

The opening of the file, as written. The whole thing — 289 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Overview

Configuration has two layers: core config (managed by the framework, env-driven) and server config (your own Zod schema for domain-specific env vars). Never merge them.

Import: AppConfig, config, parseConfig, resetConfig, ConfigSchema from @cyanheads/mcp-ts-core/config.


Core config

Managed by @cyanheads/mcp-ts-core. Validated via Zod from environment variables. Uses a lazy proxy — parsing is deferred until the first property read.

Priority (highest to lowest):

  1. name/version/title/websiteUrl/description/icons options passed to createApp() or createWorkerHandler()
  2. Environment variables
  3. package.json fields

Identity

Env Var AppConfig field Default Notes
MCP_SERVER_NAME mcpServerName package.json name Overrides package name
MCP_SERVER_VERSION mcpServerVersion package.json version Overrides package version
MCP_SERVER_DESCRIPTION mcpServerDescription package.json description Optional; createApp({ description }) wins when set
PACKAGE_NAME pkg.name package.json name Rarely needed
PACKAGE_VERSION pkg.version package.json version Rarely needed

SDK identity fields (API-only, no env var equivalent — passed to createApp() / createWorkerHandler(), forwarded to initialize and /.well-known/mcp.json):

Option Type Notes
title string? Human-readable display name shown in client listings
websiteUrl string? Canonical homepage / repository URL
description string? One-line description; wins over MCP_SERVER_DESCRIPTION when set
icons Implementation['icons']? Array of icon objects: { src, mimeType?, sizes?: string[], theme?: 'light'|'dark' }
cacheHints CacheHints? Cache hints for the 2026-07-28 cacheable results, keyed by operation — see below

Read the full file on GitHub · 289 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. 2d ago First seen · 289 lines · 43 tokens per session scan A 44f4d41d9fa6

Subscribe to this mod's changes

api-config is a skill published in the GitHub repository cyanheads/reference-data-mcp-server (1 stars, last pushed 8d ago), licensed Apache-2.0. It adds 43 tokens to every session and 5,288 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. It is 95% identical to api-config, differing in 4 lines, and is treated as a copy.

Related

Other skills, from other repositories