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DisclaimerUnofficial, and not affiliated with Anthropic. Nearly all of this is read straight out of what ships: npm bundles, captured prompts, published docs. Anthropic's own notes go in verbatim, marked as theirs. The rest is my reading, and every entry carries the strings behind it. If one looks wrong, vote it down and say why.

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Claude Code v2.1.211

--callback-port Validation Tightened

What

The MCP OAuth callback port flag (--callback-port) now validates that the port number falls within the valid TCP range [1, 65535], rather than only checking it is a positive integer.

Details
  • The error message now reads: "Error: --callback-port must be an integer in [1, 65535]"
  • Port 0 is no longer accepted. The validation expression is !Number.isInteger(m) || m <= 0 || m > 65535, so port 0, negative values, and non-integer inputs (e.g. 1.5 or non-numeric strings that parse to NaN) are all rejected.
  • The same validation is applied in two separate command paths: claude mcp add (for SSE and HTTP transports) and claude mcp oauth identity-provider set.
Evidence

Updated validation error string (search for "--callback-port must be an integer in [1, 65535]")

Strings lifted out of the shipped bundle, so the claim above can be checked against them.

See this entry in the whole of v2.1.211 →