[mcp-client] Make HF_TOKEN optional

[julien-c]

in case we pass a custom baseURL, then HF_TOKEN is actually not required.

[Copilot]

Pull Request Overview

This PR makes the HF_TOKEN environment variable optional by updating type definitions, client instantiation, CLI error handling, and documentation.

• Updated McpClient and Agent type annotations to allow an optional API key.
• Modified the CLI to require HF_TOKEN only when no ENDPOINT_URL is provided.
• Revised README to reflect the optional nature of HF_TOKEN.

Reviewed Changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
packages/mcp-client/test/McpClient.spec.ts	Removed fallback to an empty string for apiKey in tests
packages/mcp-client/src/McpClient.ts	Updated the apiKey parameter type to be optional and passed to InferenceClient
packages/mcp-client/src/Agent.ts	Updated the apiKey parameter type to be optional
packages/mcp-client/cli.ts	Changed CLI error handling to check for ENDPOINT_URL or HF_TOKEN
packages/mcp-client/README.md	Updated documentation to denote HF_TOKEN as optional

Comments suppressed due to low confidence (4)

packages/mcp-client/test/McpClient.spec.ts:13

• Previously, a fallback empty string was provided if HF_TOKEN was unset. Verify that passing undefined instead of an empty string does not lead to unexpected behavior in tests.

apiKey: process.env.HF_TOKEN,

packages/mcp-client/src/McpClient.ts:53

• Since apiKey is now optional, ensure that the InferenceClient properly handles an undefined value or consider implementing a default value if necessary.

apiKey?: string;

packages/mcp-client/src/Agent.ts:69

• As with McpClient, ensure that any usage of an undefined apiKey is handled gracefully, particularly when interfacing with services expecting a non-null token.

apiKey?: string;

packages/mcp-client/cli.ts:65

• Confirm that the new condition accurately covers scenarios where an endpoint is provided but HF_TOKEN is not; ensure that local inference providers using ENDPOINT_URL are fully supported.

if (!ENDPOINT_URL && !process.env.HF_TOKEN) {