Configuration

The server reads four environment variables. An empty string counts as unset; any other value, including whitespace, is taken literally.

Variable	Values
KLAP_ENV	unset (means test), test or live
KLAP_API_KEY	a klap_test_... or klap_live_... key
KLAP_BASE_URL	the Klap API base URL
KLAP_MCP_ALLOW_LIVE_WRITES	1 to enable live writes; anything else leaves them off

How the key is chosen

1. KLAP_ENV picks the environment. It must be exactly test or live (LIVE, live or production all refuse).
2. If KLAP_API_KEY is set, it is the only key source. ~/.klap/config.json is not read at all. KLAP_BASE_URL is required, and the key's prefix must match the environment: a klap_test_ key with KLAP_ENV=live refuses to start, and so does a klap_live_ key with KLAP_ENV unset.
3. Otherwise the key comes from ~/.klap/config.json, the slot for the chosen environment. When KLAP_ENV is unset the test slot is used. Unlike the CLI, the server never picks live on its own: if only a live key is stored, set KLAP_ENV=live. The base URL is the one stored with the key. If KLAP_BASE_URL is also set it must point to the same place (compared on origin and path, ignoring a trailing slash).

Base URL rules

Whichever base URL ends up in use must:

• parse as a URL;
• use https://, or http:// only for localhost, 127.0.0.1 or [::1];
• carry no username or password.

Live writes

In live, only read tools are registered. KLAP_MCP_ALLOW_LIVE_WRITES=1 adds charges_create, charges_check and webhooks_retry_delivery. sandbox_trigger is never available in live. In test the variable has no effect; every tool is available.

Refusals

When the configuration is unsafe or incomplete the server prints one line to stderr and exits with status 1. Messages never contain key material.

Situation	What to do
KLAP_ENV is not test/live	Fix the value
KLAP_API_KEY set, KLAP_BASE_URL missing	Set both
KLAP_API_KEY prefix unknown	Use a klap_test_/klap_live_ key
Key environment differs from KLAP_ENV	Use the matching key or change KLAP_ENV
No ~/.klap/config.json and no KLAP_API_KEY	Run klap login --api-key - --base-url <url>
Stored config has no key for the environment	klap login with that key, or change KLAP_ENV
Stored config is corrupted or has a key in the wrong slot	Run klap logout, then klap login again
~/.klap or ~/.klap/config.json is a symlink	Remove the link, then run klap login
KLAP_BASE_URL differs from the stored base URL	Unset it, or pass KLAP_API_KEY too
Base URL is http:// on a non-loopback host, or has credentials	Use https:// without credentials

Using a key without klap login

For CI or a throwaway setup you can pass the key directly. It then sits in your MCP client's config file, so prefer klap login on a workstation:

{
  "mcpServers": {
    "klap-local": {
      "command": "npx",
      "args": ["-y", "@klappay/mcp@1.0.0"],
      "env": {
        "KLAP_API_KEY": "klap_test_...",
        "KLAP_BASE_URL": "http://localhost:3000"
      }
    }
  }
}