> For the complete documentation index, see [llms.txt](https://docs.nansen.ai/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.nansen.ai/mcp/claude-tag.md).

# Claude Tag (Slack)

Use Nansen data directly inside Slack by connecting the Nansen MCP server to Claude Tag — Anthropic's native Slack integration. Once set up, any Slack channel can query Nansen without leaving the conversation.

### Prerequisites

* A Nansen API key — get yours at [app.nansen.ai/api](https://app.nansen.ai/api?tab=api)
* Admin access to your Anthropic org's Claude Tag settings

***

## Step 1 — Switch Claude in Slack to New mode

Go to [claude.ai/admin-settings/claude-tag](https://claude.ai/admin-settings/claude-tag) and make sure the **Claude in Slack version** dropdown (top-right of the page) is set to **New**.

{% hint style="warning" %}
**Legacy mode must be switched off first.** While on Legacy, the Access bundles and Connections sections are hidden and any credential you add won't be applied.
{% endhint %}

<figure><img src="/files/OmYatrVUCrvshRH4DWBp" alt="Legacy mode warning banner — settings saved but not applied"><figcaption><p>Legacy mode: settings are saved but won't apply until you switch to New</p></figcaption></figure>

<figure><img src="/files/vuhQDqm16hwmPwpxGmWv" alt="Claude Tag access page with version set to New"><figcaption><p>After switching to New: Access bundles section is now active</p></figcaption></figure>

***

## Step 2 — Add the Nansen API credential

From the Claude Tag sidebar, go to **Access Bundle** and create a new bundle or select an existing bundle you'd like to use. Open the **Credentials** tab and click **+ Connect another app**.

<figure><img src="/files/ipOAHZ0j8NEineWONzs8" alt="Access Bundle dropdown showing Create new bundle option"><figcaption><p>Access Bundle menu — create a new bundle or select an existing one</p></figcaption></figure>

<figure><img src="/files/BD3YeGXorveJHEDrDQbn" alt="Bundle Credentials tab with Connect another app button"><figcaption><p>Credentials tab — click "+ Connect another app"</p></figcaption></figure>

Fill in the form as follows:

| Field                   | Value                   | Notes                                       |
| ----------------------- | ----------------------- | ------------------------------------------- |
| Name                    | `Nansen`                | Any label works                             |
| Credential type         | `Bearer`                | Required to unlock the Custom headers field |
| Allowed websites        | `mcp.nansen.ai`         | Credential is sent only to this host        |
| Custom headers — Name   | `NANSEN-API-KEY`        |                                             |
| Custom headers — Prefix | *(leave blank)*         | Pre-filled with "e.g. Bearer" — clear it    |
| Custom headers — Value  | `<your Nansen API key>` | Paste your Nansen API key here              |

<figure><img src="/files/KApfbCTrAeZf6TvZJpg9" alt="Filled-in Connect an app form showing Nansen, Bearer, mcp.nansen.ai, and NANSEN-API-KEY header"><figcaption><p>Filled form — Name, Bearer type, allowed website, and custom header</p></figcaption></figure>

{% hint style="info" %}
**Why Custom headers?** The Nansen MCP server reads a `NANSEN-API-KEY` header directly — it does not use standard Bearer token authentication. Selecting **Bearer** as the credential type is what unlocks the Custom headers field.
{% endhint %}

After saving, navigate back to [claude.ai/admin-settings/claude-tag](https://claude.ai/admin-settings/claude-tag) and enable the access bundle. Under **Access summary**, **Connections** should show **Nansen**.

<figure><img src="/files/QIZSC4l6X9hXd75ui3qh" alt="Final state: version New, Slack Default bundle active, Nansen shown in Connections"><figcaption><p>Done — version=New, bundle enabled, Nansen connection active in Access summary</p></figcaption></figure>

***

## Step 3 — Invite Claude to a Slack channel

In any Slack channel where you want Nansen access, run:

```
/invite @Claude
```

***

## Step 4 — Verify

Tag Claude in the channel and ask a Nansen question:

> **@Claude** what tokens are smart money buying on Ethereum today?

Claude will call the Nansen MCP server and return live data directly in Slack.

{% hint style="warning" %}
If Claude responds without data or says it can't access Nansen, double-check that the access bundle is enabled and that the `NANSEN-API-KEY` header value is correct.
{% endhint %}


---

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