> ## Documentation Index
> Fetch the complete documentation index at: https://nexus.gerowallet.io/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# MCP Server

> Connect Claude and other AI agents to Nexus via the Model Context Protocol

**MCP Server add-on.** Nexus exposes a [Model Context Protocol](https://modelcontextprotocol.io) (MCP) server so AI agents (Claude Desktop, Claude Code, or any MCP client) can query Cardano, Bitcoin, Midnight, and market data, and build transactions, as native tools.

<Note>
  The MCP endpoint requires the **MCP Server** add-on. Calls without it fail with the JSON-RPC error `{"errorCode": "mcp_addon_required"}`. The single MCP add-on unlocks **all** tools below; you do **not** need the Market Data or Transaction Builder add-ons separately to use their MCP tools.
</Note>

## Connecting

* **Endpoint:** `https://nexus.gerowallet.io/mcp/`
* **Auth:** your Nexus API key in the `X-Api-Key` header (keys start with `nxs_`)

Example Claude Desktop / Claude Code config:

```json theme={null}
{
  "mcpServers": {
    "nexus": {
      "url": "https://nexus.gerowallet.io/mcp/",
      "headers": { "X-Api-Key": "nxs_your_api_key_here" }
    }
  }
}
```

Health check: `GET /mcp/health` (no add-on required).

## Tools

The server registers **25 tools** across six domains.

### Cardano (8)

`cardano_account_info` · `cardano_account_history` · `cardano_address_info` · `cardano_asset_info` · `cardano_block_info` · `cardano_epoch_info` · `cardano_pool_info` · `cardano_tx_info`

### Bitcoin (4)

`bitcoin_balance` · `bitcoin_tx_info` · `bitcoin_fee_estimate` · `bitcoin_utxos`

### Market Data (4)

`market_price` · `market_ohlcv` · `market_pair_list` · `market_top`

### Midnight (4)

`midnight_info` · `midnight_dust_status` · `midnight_build_unshielded` · `midnight_submit`

### Transaction Builder (2)

`cardano_build_unsigned` · `cardano_preview_tx`

### Account (3)

`me` · `my_api_keys` · `my_subscription`

<Note>
  Tool calls count against your plan's request quota and rate limit like any other API usage, and every call is audit-logged.
</Note>