DataLLM LabDeepSeek in Cursor: Chat Setup and Agent Mode Checks
DeepSeek's OpenAI-compatible API is not, by itself, proof that a DeepSeek model works in Cursor Agent mode. Cursor documents bring-your-own keys for named providers, but does not name DeepSeek in that list. Treat a custom endpoint as a version-specific integration to check. This guide gives the current provider values, a staged verification checklist, and clear stop and rollback conditions.
What the official documentation establishes
Cursor's API-key help page names OpenAI, Anthropic, Google, Azure OpenAI, and AWS Bedrock. It describes custom keys for chat models, while Tab keeps using built-in models. DeepSeek's API introduction documents protocol compatibility. Neither document establishes a completed DeepSeek-to-Cursor Agent run.
Separate three questions when troubleshooting: can this account authenticate with DeepSeek, can this Cursor version send chat to the custom endpoint, and can the selected mode complete the tool loop? A positive answer to one does not answer the others.
| Claim | Evidence in this guide | What is still needed |
|---|---|---|
| DeepSeek exposes an OpenAI-compatible endpoint | DeepSeek documentation | Your account's access and quota |
| Cursor supports BYOK for its named providers | Cursor documentation | Available models for your account |
| A custom DeepSeek chat request works in your installed Cursor | Not tested here | Version-specific configuration and a successful request |
| DeepSeek drives a complete Cursor Agent workflow | Not tested here | Model selection, tool-call, result-return, and completion evidence |
| A DeepSeek key replaces Cursor Tab | Not supported by the documented BYOK scope | Do not promise this behavior |
This is a documentation-grounded setup checklist, not a hands-on success report. No Cursor account, API key, or model request was used for this revision.
Record the setup before changing settings
Keep this record locally. Leave credentials out of screenshots, bug reports, and shared logs.
Cursor version / build:
Operating system:
Plan type (individual / Teams / Enterprise):
Selected mode and model shown in the picker:
Provider configuration used:
OpenAI-compatible base URL:
Exact model ID:
Time of check:
Request ID / sanitized error:
Previous configuration for rollback:
Result: not tested / passed this check / failed this check
The current official flow for a named provider is Settings > Models, choose the provider, paste its key, and Save. Unlike the previous version of this article, these current instructions do not include a "Verify" step. A custom base-URL field or model-name control must actually exist in your installed version before the DeepSeek route below is relevant.
Do not paste a DeepSeek key into an OpenAI provider entry and assume that changes the destination. Check the base URL as well. If your version does not expose a usable custom endpoint configuration, stop: this page does not establish a hidden switch or supported workaround.
Current DeepSeek base URL and model IDs
The DeepSeek getting-started page lists these values, checked October 15, 2026:
| Setting | Documented value | How to use this information |
|---|---|---|
| OpenAI-compatible base URL | https://api.deepseek.com |
Candidate value for a tool's OpenAI-compatible endpoint field |
| Chat model | deepseek-flash |
Current Flash identifier in the getting-started guide |
| Alternative model | deepseek-v4-pro |
Another documented model identifier; not a Cursor Agent certification |
| Anthropic-compatible base URL | https://api.deepseek.com/anthropic |
A different protocol route; do not substitute it into an OpenAI-only field |
The legacy deepseek-v4-flash and deepseek-v4-flash-vision-exp names are still accepted according to DeepSeek, but their original models have retired. Requests are served by DeepSeek-V4.1-Flash and billed at the Flash rate. Prefer the current identifier instead of treating an old alias as a frozen model version.
The previous advice that a July retirement date was "essentially now" has been removed. No account-level alias resolution was tested for this guide.
For the meaning of a base URL, see the OpenAI-compatible API explainer. Protocol compatibility describes request transport, not support for every editor feature.
Check an endpoint's shape without sending credentials
Download the offline endpoint-shape checker and tests. It accepts only the documented DeepSeek OpenAI-compatible base forms, refuses credentials, query strings, fragments and the Anthropic route, and prints the candidate chat URL. It does not contact DeepSeek or configure Cursor.
python3 endpoint_shape.py https://api.deepseek.com
python3 -m unittest -v test_endpoint_shape.pyThis catches a common field mismatch: a base URL is not a full /chat/completions path. It also prevents accidentally presenting the Anthropic path as an OpenAI endpoint. A clean shape check is not authentication, account access or Agent compatibility; those still require the separate checks below.
Check chat before checking Agent mode
Use a throwaway workspace containing no private files. Set a small provider budget before testing; the following procedure can create billable requests and was not executed for this article.
- Confirm the endpoint and model ID from current provider documentation. Keep the previous working editor configuration available.
- If your Cursor version permits a custom endpoint and model, enter the values above and select that exact model in the chat picker. Otherwise stop rather than guessing at UI labels.
- Send a short, non-sensitive prompt such as "Return only the word READY." A reply checks a basic chat path, not tool support or model quality.
- Record the sanitized request result and inspect the provider's usage record where available. If the destination or selected model cannot be established, mark the result inconclusive.
- Restart the session before moving to a different mode. Keep the model selection explicit rather than assuming a working chat selection applies everywhere.
A valid provider key does not prove that the editor used that key. A reply attributed to an automatic or built-in model is not evidence that DeepSeek handled the request.
How to get DeepSeek working with Cursor Agent mode: the missing checks
There is no verified one-click recipe in this article. First establish the chat path, then test only the Agent behavior your installed version exposes. Do not describe every Agent feature as proprietary or every BYOK model as supported; both statements exceed the cited documentation.
In the throwaway workspace, create a harmless text file containing a known marker. Ask the selected mode to read that file and report the marker without changing files or running a shell command. Approve only the read operation if the interface asks. Stop if it proposes a write, command execution, external connection, or broader file access.
| Check | Evidence to retain | A failure means |
|---|---|---|
| Custom model remains selected in Agent mode | Version, mode, and picker state | The chat setup did not carry into this mode |
| A file-read tool is actually called | Sanitized tool event, not just a plausible answer | Text completion alone did not establish tool use |
| The tool result returns to the model | Tool result and subsequent answer | The loop may be incomplete even if a tool call occurred |
| The final answer matches the marker | Expected versus actual text | This minimal task did not complete correctly |
| No disallowed operation occurs | Workspace diff and allowed-operation record | The test violated its safety boundary |
Passing this read-only check would establish only that one path on one version and account. It would not prove multi-file editing, command execution, long-context reliability, or production readiness. Test those separately only with authorization and an appropriate sandbox.
Sort failures by layer and restore the known-good setup
| Failure | Check next | What not to conclude |
|---|---|---|
| Provider rejects the credential | Account access, key scope, quota; update or revoke locally | "Cursor Agent is unsupported" |
| Endpoint/path or model not found | Protocol field, base URL, exact current model ID | "Try every legacy name until one works" |
| Chat works but Agent rejects the model | Mode-specific selection and supported features in that version | "A gateway will automatically fix it" |
| A tool call occurs but cannot finish | Tool schema, permissions, and return path | "Authentication succeeded, so Agent works" |
| Output names a different model | Selection and provider-side evidence | "The custom endpoint must have handled it" |
Restore the previous provider settings and built-in model selection if the integration fails. Keep a sanitized record of the failed layer so the next check changes one variable. If direct DeepSeek use is more important than this editor, its official agent integration guide documents other supported routes; it does not certify Cursor by association.
BYOK billing and privacy are part of the decision
Cursor's current API-key help distinguishes individual plans from team plans. Individual plans, including Premium, Super, Ultra and the legacy Pro/Pro+ tiers, pay the provider's model cost without drawing from included usage or prepaid credit. Teams and Enterprise also apply the $0.25 per million input, output and cached tokens Cursor Token Rate. On a team using The X Subscription, that fee uses prepaid credit; legacy Teams uses the Other Models allowance and its on-demand settings. Check the actual plan rather than treating every team allowance as identical. Cursor BYOK billing, checked October 15
BYOK is not a local-only data path. Cursor says its Zero Data Retention policy does not apply to these requests; provider terms govern handling. The key and request transit Cursor's backend for prompt building, though the key is not persisted after completion. Cursor key and data handling
For a work repository, get approval for the actual route before testing. Include any gateway in that data review. A compatibility label does not settle retention, location, or access permissions.
A gateway is another route to evaluate, not an Agent fix
Adding a gateway changes the endpoint, credentials, billing, and possibly routing. It does not give an unsupported custom model a Cursor feature it lacked. Establish chat and the read-only tool loop again for that route, and record the actual destination model. Do not enable silent fallback during a diagnostic test.
The routing and failover guide and coding-agent cost guide explain those separate concerns. This article does not claim an official DataLLM Lab integration or a successful gateway-backed Cursor Agent run.
FAQ
Does this guide prove DeepSeek works in Cursor Agent mode?
No. It supplies current provider values and a verification procedure. A completed chat request, tool call, and returned result must be established on the installed Cursor version and account.
Which DeepSeek model ID should I start with?
The current getting-started guide lists deepseek-flash and deepseek-v4-pro. That is provider documentation, not confirmation that either works in every Cursor mode.
Can changing to a gateway fix an Agent rejection?
Not necessarily. An endpoint change cannot establish mode support. Repeat the selection, chat, and tool-loop checks instead of claiming a guaranteed fix.