Add support for --header flags in MCP Inspector CLI#716
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olaservo merged 6 commits intoAug 29, 2025
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philfreo
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- Add --header option to both wrapper CLI (cli.ts) and main CLI (index.ts) - Support multiple headers with "HeaderName: Value" format validation - Pass headers to HTTP and SSE transports via requestInit.headers - Add parseHeaderPair function for proper header parsing - Fix output truncation issue by removing forced process.exit(0) - Update types to include headers in Args and TransportOptions Usage: --header "Authorization: Bearer token" --header "X-Custom: value"
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- Document --header flag usage with examples - Explain header format requirements - Clarify transport support (HTTP, SSE, not STDIO) - Add authentication examples with API keys and bearer tokens
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| process.exit(0); | ||
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| // Let Node.js naturally exit instead of force-exiting | ||
| // process.exit(0) was causing stdout truncation |
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Originally I think this was added because it was hanging on CI, however I am not seeing that behavior in the pipeline here when the tests run.
Looking at the past commits where the process.exit(0) was added, this was the test failure that happened: https://github.com/modelcontextprotocol/inspector/actions/runs/16283307379/job/45977026872
Which doesn't happen anymore, so it may not have been needed in the first place? But we should keep an eye out for anything that might be intermittent.
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Closes #420
Summary
Adds support for (multiple)
--headerflags to the MCP Inspector CLI, enabling custom HTTP headers for authentication and other purposes.Changes
--headeroption to both wrapper CLI and main CLI with "HeaderName: Value" format validationrequestInit.headersprocess.exit(0)Usage
Testing
Example Use Case
This enables authentication with MCP servers that require API keys or other custom headers: