The `delete` property of issue_write's issue_fields items was declared with
Enum: []any{true}, making true its only legal value. The property is optional,
but a client that fills every property of a schema -- common, since
OpenAI-style strict function calling requires every property to appear in
`required` -- had no way to express "not deleting this field": there is no
false in the enum and no null in the type. `value` offers no alternative
either, being typed ["string","number","boolean"] with no null.
The MCP Go SDK validates arguments against the resolved input schema before
the handler runs, so delete: false was rejected at schema validation and never
reached optionalIssueWriteFields. Such clients sent delete: true alongside a
value instead and hit the handler's mutual-exclusion check, so issue_write
could never set an issue field for them.
Remove the enum so false is a legal no-op, and document that omitting the
property or setting it to false leaves the field unchanged. No handler change
is needed: the code already branches on `if deleteField`, so false falls
through to the normal value path, and the mutual-exclusion check for
delete: true still applies. Add tests for optionalIssueWriteFields, which had
none.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Travis Gockel
9cfe97e20a