> For the complete documentation index, see [llms.txt](https://andrewkimjoseph.gitbook.io/celina-sdk/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://andrewkimjoseph.gitbook.io/celina-sdk/guides/mcp-session-wallet.md).

# MCP session wallet

This guide applies to [**celina-mcp**](https://www.npmjs.com/package/@andrewkimjoseph/celina-mcp) when you run it locally with `CELO_PRIVATE_KEY` in the MCP server `env`. It does **not** apply to browser apps that use this SDK directly.

## SDK vs MCP vs hosted

| Runtime                                   | Who is “the user”?       | How the wallet is known                                                                               |
| ----------------------------------------- | ------------------------ | ----------------------------------------------------------------------------------------------------- |
| **celina-sdk** / `surface: "browser"`     | Connected browser wallet | You pass `0x…` on every read/prepare (e.g. wagmi `useAccount()`); no `get_wallet_address`             |
| **celina-mcp** stdio + `CELO_PRIVATE_KEY` | MCP server signer        | Omit `address` / `wallet_address` / `from` on wallet-scoped tools; they default to the configured key |
| **Hosted MCP** (`mcp.usecelina.xyz`)      | N/A (no server key)      | Pass explicit addresses on every wallet-scoped tool; key-dependent tools fail without local keys      |

Browser agent hosts use the same tool catalog with `surface: "browser"` — see [Tool catalog](/celina-sdk/guides/tool-catalog.md). They do not run celina-mcp and do not use `get_wallet_address`.

## `get_wallet_address`

Read-only MCP tool with **no parameters**. Returns:

```json
{
  "wallet_address": "0x…",
  "has_wallet": true,
  "source": "CELO_PRIVATE_KEY"
}
```

Call it when the agent needs the signer address as **data** (logging, comparisons, copy-paste). For everyday “my balances”, omit address fields instead.

Fails with a clear error when `CELO_PRIVATE_KEY` is not set (hosted endpoint or read-only stdio).

## Omit address on wallet-scoped tools

When `CELO_PRIVATE_KEY` is configured, these parameters are **optional** and default to the signer:

| Parameter     | Example tools                                                                                                                          |
| ------------- | -------------------------------------------------------------------------------------------------------------------------------------- |
| `address`     | `get_account`, `get_celo_balances`, `get_stablecoin_balances`, `get_token_balance`, staking reads, GoodDollar reads, `get_nft_balance` |
| `from`        | `estimate_transaction`                                                                                                                 |
| `fromAddress` | `call_contract_function`, `estimate_contract_gas`                                                                                      |

Pass an explicit value to query a **different** wallet.

## Agent rules

* Never derive addresses from shell commands or read `.env`.
* Do not call `get_wallet_address` on every turn unless you need the string; prefer omitted params for “my” operations.
* On hosted MCP (no key), always pass explicit `address` / `wallet_address`.

## Related

* [Architecture](/celina-sdk/concepts/architecture.md) — Celina stack
* [celina-mcp README](https://github.com/andrewkimjoseph/celina-mcp#session-wallet-local-stdio) — MCP setup and tool table


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