How to use GPT-5.6 in Cursor: setup for Sol, Terra and Luna

Cursor is useful when you want an agent inside the editor; GPT-5.6 is useful when the task needs repository-scale coding and tool use. AnyModel connects the two through one OpenAI-compatible endpoint, so Sol, Terra and Luna can share the same key and billing balance.

The practical advantage is not merely access to another model. Once the provider is configured, you can choose a cheap worker for routine edits and a frontier tier for the difficult review without adding another vendor account.

GPT-5.6 model ids for Cursor

Add the exact id for each model you want to expose in Cursor:

Terra is the safest default if you have not evaluated the family yet. A larger context window does not require sending an entire repository: include only the code and instructions the task actually needs.

Option A: use the AnyModel Cursor installer

AnyModel can write the custom endpoint and selected model into Cursor's local state. Close Cursor first, then run:

bash <(curl -fsSL "https://anymodel.org/i?tool=cursor&model=gpt-5.6-terra") <YOUR_API_KEY>

The installer creates a timestamped backup before changing Cursor's local configuration. Reopen Cursor after it finishes and check the model picker.

Local application formats can change between Cursor releases. If the automated route does not match your version, use the manual setup below rather than repeatedly modifying the state database.

Option B: configure Cursor manually

Cursor's labels move occasionally, but the required values remain the same:

1. Open Cursor Settings and find the models or API provider section.
2. Add or enable an OpenAI-compatible provider.
3. Set the base URL to https://anymodel.org/v1.
4. Paste your AnyModel API key.
5. Add gpt-5.6-terra, gpt-5.6-sol and gpt-5.6-luna as custom model ids.
6. Verify the provider and select a model in the chat or agent picker.

You receive an AnyModel key, not an OpenAI key. If Cursor has separate fields for the official OpenAI provider and a custom provider, put the key in the custom provider that uses the AnyModel base URL.

Verify the endpoint before debugging Cursor

Test the same key and model with a direct request:

curl https://anymodel.org/v1/chat/completions \
  -H "Authorization: Bearer $ANYMODEL_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "gpt-5.6-terra",
    "messages": [{"role": "user", "content": "Reply with the word READY."}]
  }'

If this returns a completion, the account, key and route work. The remaining issue is in Cursor's provider selection or cached settings. If it fails, solve the API error before changing editor options.

Route tasks by difficulty

Using one model for every Cursor interaction is simple but inefficient. Try this policy:

• Luna for narrow inline edits, test cases, documentation cleanup and extraction;
• Terra for normal Agent mode tasks, debugging and multi-file features;
• Sol for ambiguous migrations, architecture changes, repeated failures and final review.

For an honest comparison, give Sol and Terra the same repository state, prompt, test command and acceptance criteria. Compare the resulting diffs and human corrections, not just the explanation in chat. The GPT-5.6 pricing guide includes a token-cost example.

Common Cursor problems

Verification fails immediately. Confirm the base URL ends at /v1, not /v1/chat/completions. Re-copy the key without whitespace.

The model does not appear. Add the exact id to the custom model list, enable it, then fully restart Cursor. Model lists and provider settings may be cached.

Cursor uses a bundled model instead. Check the active picker after opening a new chat. A successful provider verification does not automatically change the selected model in every workspace.

The model returns text but tool behavior is weak. Start with a bounded agent task and explicit test command. Not every client exposes every provider-specific tool feature identically through a compatible API.

Costs are hard to predict. Agent mode can send many sequential requests and repeat repository context. Use the live pricing table, then measure a real session rather than multiplying a single prompt size.

Privacy and repository safety

Commit or otherwise preserve the working tree before an agent edits it. Exclude secrets and generated data from context. Ghost Mode disables prompt and response retention on the AnyModel side, but the selected upstream provider still processes the request.

Once Cursor is connected, adding another model does not require another key or base URL. Change the model id, test the same task and keep the tier that produces the safest patch at an acceptable total cost. Create a free AnyModel key to run the first comparison.