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To use Claude Opus or Claude Fable in Slashy’s agent chat, you bring your own Anthropic API key. Slashy doesn’t bill for that usage, Anthropic does. This guide walks through creating the key and adding it to Slashy.
You only need this if you want Opus or Fable. The other models in the picker need no key and no setup. See AI models in Slashy.

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Create the key

1

Sign in to the Anthropic Console

Go to console.anthropic.com and sign in, or create an account if you don’t have one. This is Anthropic’s developer console — separate from your Claude.ai chat account.
2

Add billing

API usage is pay-as-you-go and billed by Anthropic, so the console asks you to add a payment method and some credit before keys will work. Open Billing (or Plans & Billing) and add a card or buy credits.
3

Open API Keys

Go to Settings → API Keys (at console.anthropic.com/settings/keys).
4

Create a key

Click Create Key, give it a name you’ll recognize later (e.g. Slashy), and create it.
5

Copy it now

Copy the key the moment it’s shown — it starts with sk-ant-. Anthropic only displays the full key once; if you lose it, you’ll have to create a new one.
Treat the key like a password. Anyone with it can spend against your Anthropic account. Don’t paste it into chats, screenshots, or shared docs.

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Add the key to Slashy

The first time you pick Opus or Fable, Slashy asks for the key right in the agent chat. Paste it there.
1

Open the model picker

Click the model name at the bottom of the agent chat message box (Cmd+/ opens the chat).
2

Select Opus or Fable

Models that need a key show a key icon.
3

Paste your key

Paste the sk-ant- key and click Save. It’s stored on your account only.
You can also add or remove the key any time under Settings → Integrations, in the Claude API key card. See AI models in Slashy for more.

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Costs and limits

  • You pay Anthropic directly. Opus and Fable usage is billed to the Anthropic account that owns the key, at Anthropic’s published per-token rates. Slashy adds nothing on top.
  • Watch your usage in the Anthropic Console under Usage. You can set spend limits there to cap monthly cost.
  • New accounts sometimes start with a low rate limit. If Opus or Fable replies fail with a rate-limit error, raise your limit in the console or add more credit.

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Troubleshooting

AI models in Slashy

Choose a model and manage your key.

Customize the agent

Tune voice and instructions.

AI privacy

How your data and BYOK requests are handled.

Slashy MCP

Use Slashy’s tools from Claude and other AI clients.