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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 v2.1.219

SDK init message reports skipped MCP server configs

Use it now
Useful4 Signal0
SDK Notable

SDK callers get an mcp_server_errors array naming rejected MCP configs, so CI can fail on it.

mcp_server_errors
What

The system/init SDK message now carries mcp_server_errors, so a programmatic caller can see which MCP config entries were rejected at validation time rather than silently getting fewer servers.

Details
  • each element is {name, type, message} for a config entry that failed validation and was skipped
  • entries whose server did connect anyway are filtered out of the array
  • the MCP config loader tags validation failures with a stable code, adding "invalid_config" alongside the existing categories
  • the schema note says the key is omitted when empty, and that "CI can fail on (mcp_server_errors?.length ?? 0) > 0"
  • the REPL bridge currently passes an empty list, so this is populated on the SDK path only
Evidence

mcp_server_errors

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

Related

Other releases about the same thing. Found by shared names or similar wording; neither means one caused the other.

See this entry in the whole of v2.1.219 →