MCP server.

On top of the models, NaN exposes its own tools through an MCP server (Model Context Protocol). It is for the opposite of the rest of this section: here you are not giving your agent models, you are giving it capabilities.

Today the available tool is web search. The registry will grow, so ask the server what it has rather than trusting this sentence.

Field	Value
URL	`https://api.nan.builders/mcp`
Authentication	`Authorization: Bearer sk-your-key`
Transport	HTTP, stateless

This URL has no /v1 The MCP server lives at the root of the domain, not under /v1 like the rest of the API. It is https://api.nan.builders/mcp, nothing else.

The key is the same one you use for the models. There is no second key to generate.

Generic configuration

Almost every MCP client uses this same file, with this same block:

{
  "mcpServers": {
    "nan": {
      "url": "https://api.nan.builders/mcp",
      "headers": {
        "Authorization": "Bearer sk-your-key"
      }
    }
  }
}

Where that file goes depends on the client:

Client	Where
Cursor	`.cursor/mcp.json` in the project, or `~/.cursor/mcp.json`
Cline	The MCP Servers panel inside the extension
Zed	The `context_servers` block of `~/.config/zed/settings.json`
OpenCode	The `mcp` block of your `opencode.json`

Claude Code

Claude Code adds it from the command line:

claude mcp add --transport http nan https://api.nan.builders/mcp \
  --header "Authorization: Bearer sk-your-key"

Add --scope user if you want it available in every project and not only the current one. Inside a session, /mcp shows you the connected servers and the tools they offer.

This is independent of the models: you can use NaN’s web search from Claude Code even if your models come from somewhere else.

Check that it works

With no client in between, by asking the server directly which tools it has:

curl https://api.nan.builders/mcp \
  -H "Authorization: Bearer $NAN_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{ "jsonrpc": "2.0", "id": 1, "method": "tools/list" }'

The answer carries the list of tools with their arguments. That is where you always see the real set, which is more reliable than any hand-written list.

And a real search:

curl https://api.nan.builders/mcp \
  -H "Authorization: Bearer $NAN_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "jsonrpc": "2.0",
    "id": 2,
    "method": "tools/call",
    "params": {
      "name": "web_search",
      "arguments": { "query": "kubernetes 1.34 release", "count": 5 }
    }
  }'

The `web_search` tool

It takes the same arguments as the POST /v1/search endpoint:

Argument	What it does
`query`	The search. The only mandatory one
`count`	How many results, from 1 to 20. Default 5
`freshness`	Age filter: `pd` day, `pw` week, `pm` month, `py` year
`fetch_content`	With `true`, it brings the text of the pages as well as the summary. It takes longer

Searches go out through NaN, so your key never talks to an external search engine and you do not need to sign up for one.

Limits

Web search has its own budget, separate from the models’: 20 requests per minute, 3 at once and 500 searches a day per key. Searching does not spend your chat quota, nor the other way around.

It makes no difference whether the call comes in through MCP or through POST /v1/search: it counts the same, on the same counter. A search repeated within the next 15 minutes is served from a short cache and arrives marked cached: true, but it still counts.

If you go over, the answer is a 429 with a Retry-After header telling you how long to wait.

Known issues