Hosted MCP server

The hosted MCP server gives a coding agent, such as Claude Code, Codex or Cursor, Drex's decide and list_models tools from one URL. Nothing installs on your machine. The server runs at https://console.nace.ai/mcp and speaks streamable HTTP.

An agent can use it before you have an API key. Add the URL, and the agent can call decide within the free limits below. When it reaches them, the tool tells the agent to ask you for a key and says how to add it. With a key, calls run on your account at your own limits and billing.

{
  "mcpServers": {
    "drex": { "url": "https://console.nace.ai/mcp" }
  }
}

claude mcp add --transport http drex https://console.nace.ai/mcp

Free limitsCopy Anchor Link

Calls without a key run on a Nace account that pays for them. Each network gets its own budget, counted by the address the request comes from.

A call over a limit is refused before it reaches the model. A refused call does not count against the day's budget when it was refused for speed. The server may also refuse free calls when many people are using them at once, or when the free tier is switched off. A key avoids all of these.

The free tier covers decide. list_models is free with or without a key.

When the limit is reachedCopy Anchor Link

decide returns an error result, not a protocol error, so the agent reads it and acts on it. The text names the limit, says when it resets, and tells the agent to ask you to:

1. Create a free API key under API Keys in the dashboard. New accounts get $25.00 of signup credit, as the Quickstart explains.
2. Add the key to this server's config, as one of the ways below.
3. Ask again.

A successful free call carries a free_tier object with calls_left_today and a link to the API Keys page.

Add your API keyCopy Anchor Link

A key starts with nace_sk_. Send it as Authorization: Bearer nace_sk_... on every request. Calls then run on your account, with no free limits and no 32 KB cap (the API's own limits apply), and spend your credit at the normal per-token price. See Authentication for creating and rotating keys.

{
  "mcpServers": {
    "drex": {
      "url": "https://console.nace.ai/mcp",
      "headers": { "Authorization": "Bearer ${env:NACE_API_KEY}" }
    }
  }
}

claude mcp add --transport http drex https://console.nace.ai/mcp \
  --header "Authorization: Bearer nace_sk_..."

[mcp_servers.drex]
url = "https://console.nace.ai/mcp"
bearer_token_env_var = "NACE_API_KEY"

Codex reads the key from NACE_API_KEY in the environment it runs in. To write the server from the command line instead, run codex mcp add drex --url https://console.nace.ai/mcp --bearer-token-env-var NACE_API_KEY.

For a client that cannot set headers, such as a custom connector in Claude, use the URL form:

https://console.nace.ai/mcp?api_key=nace_sk_...

A key in a URL can end up in the client's logs, in browser history and in screenshots. Use a header when the client allows one, and keep a URL key out of files you commit. If a key leaks, revoke it under API Keys and create another. A header wins over ?api_key= when both are present.

If the server refuses the key, decide says so and tells the agent to ask you for a new one. A key whose account has no credit gets a link to the Billing page.

ToolsCopy Anchor Link

decide takes the same arguments as the decide tool of nace-mcp, state, questions and an optional model, except images: the hosted server can't read files on your machine, so Drex Max images go through nace-mcp, the API or an SDK. Ask questions describes the question types and the answers. The server forwards the call to POST /v1/systemone, so the errors of the API apply to a call with a key.

Calls made through this server show drex-mcp in the user agent of the request log.

Hosted or localCopy Anchor Link