A 10-minute checklist before you point a coding agent at a custom gateway

#tutorial #api #webdev #ai

Disclosure and availability: DaoXE is a multi-model multi-protocol API gateway we operate (Chat Completions, Responses, Anthropic Messages, and related surfaces). It is listed on models.dev as daoxe with api=https://daoxe.com/v1. It is not available in mainland China. This article is for developers in regions allowed by the service terms.

You paste a custom base URL into a coding agent.

It fails.

The failure is usually not “the gateway is down.” It is usually a pre-flight problem: protocol, path, key name, or model id.

This is the 10-minute checklist I run before I open the agent UI.

Series context

Smoke test
Multiprotocol
Client setup
curl OK, IDE fails
Claude protocol
models.dev + /models
This post: pre-flight for coding agents

Minute 1–2: Name the client dialect

Client style	Usually needs
OpenAI-compatible coding tools	Chat Completions + Bearer key + base with `/v1`
Anthropic-shaped tools	Messages + `x-api-key` + `anthropic-version`
Catalog-driven tools	provider key (e.g. `daoxe` on models.dev) + env name

Do not configure Claude Messages settings for a Chat Completions-only client.

Minute 3–4: Auth + host with curl

export DAOXE_API_KEY="your_api_key"
export DAOXE_BASE_URL="https://daoxe.com/v1"

curl --fail-with-body --show-error --silent \
  -H "Authorization: Bearer $DAOXE_API_KEY" \
  "$DAOXE_BASE_URL/models"

Pass: HTTP 200 and model ids.

Fail: fix key / host before opening the agent.

Minute 5–6: One generation, exact model id

export DAOXE_MODEL="paste_exact_id_from_models"

curl --fail-with-body --show-error --silent \
  -H "Authorization: Bearer $DAOXE_API_KEY" \
  -H "Content-Type: application/json" \
  -d "{
    \"model\": \"$DAOXE_MODEL\",
    \"max_tokens\": 8,
    \"messages\": [{\"role\":\"user\",\"content\":\"Reply with OK.\"}]
  }" \
  "$DAOXE_BASE_URL/chat/completions"

Only a green curl here is permission to touch the agent config.

Minute 7–8: Clone the triple once

Field	Example
Base URL	`https://daoxe.com/v1`
Key	env / secret store, not committed
Model	exact id from `/v1/models` now

Public notes for common clients:

Minute 9–10: One agent only

Do not fan out to five tools.

Configure one agent. Confirm a one-line reply. Then clone the working triple.

Common fails after this checklist

Fail	Usually means
Double `/v1`	client already appends path
model_not_found	stale id from a blog
401 in agent, 200 in curl	wrong key field / env name
Claude client fails after chat works	wrong protocol surface