[mcp-client] Allow arbitrary endpoint via URL (in both McpClient and Agent)

[julien-c]

for local AI for instance 🔥

To try it

Using LM Studio + this model: https://lmstudio.ai/model/qwen2.5-14b-instruct

# in ./packages/mcp-client
ENDPOINT_URL=http://localhost:1234/v1 MODEL_ID=qwen2.5-14b-instruct tsx cli.ts

[HuggingFaceDocBuilderDev]

The docs for this PR live here. All of your documentation changes will be reflected on that endpoint. The docs are available until 30 days after the last update.

[Wauplin]

🫠

[julien-c]

cc @coyotte508 if he has an idea to "fix" (in a later PR?)

[coyotte508]

I also had to write something like this in #1322 I think (before the force-push)

[hanouticelina]

👍

[julien-c]

CI red on main so merging :)

[redthing1]

I tried this, I got this error:

Error: We have not been able to find inference provider information for model qwen3-30b-a3b.
    at getInferenceProviderMapping (/code/huggingface.js/packages/inference/dist/index.cjs:1406:11)
    at process.processTicksAndRejections (node:internal/process/task_queues:105:5)
    at async makeRequestOptions (/code/huggingface.js/packages/inference/dist/index.cjs:1462:7)
    at async innerStreamingRequest (/code/huggingface.js/packages/inference/dist/index.cjs:1699:25)
    at async chatCompletionStream (/code/huggingface.js/packages/inference/dist/index.cjs:2031:3)
    at async Agent.processSingleTurnWithTools (/code/huggingface.js/packages/mcp-client/src/McpClient.ts:2:2634)
    at async Agent.run (/code/huggingface.js/packages/mcp-client/src/Agent.ts:8:1013)
    at async main (/code/huggingface.js/packages/mcp-client/cli.ts:4:259)

Node.js v23.9.0
 ELIFECYCLE  Command failed with exit code 7.
 ```

[Wauplin]

Hi @redthing1 , could you open a new issue for this + provide the command line/script you are using? Will be easier to help you this way.