* Cast variadic tool parameters element-by-element
SchemaGenerator::buildVariadicParameterSchema() already advertises a
variadic parameter (e.g. `int ...$scores`) as a JSON "array" schema, so
a spec-conformant client sends an array for it. But
ReferenceHandler::prepareArguments() never special-cased
ReflectionParameter::isVariadic(): it fell through to the regular
single-value branch and passed the whole array to castArgumentType(),
which tried to cast it as one scalar and failed - e.g. "Cannot cast
value to integer" for `int ...$scores` given [1, 2, 3].
Any tool handler declaring a variadic parameter was therefore
unreachable through the advertised schema, confirmed by direct
reproduction against ReferenceHandler::handle() before this change.
Casts each array element individually via the existing
castArgumentType() (unchanged - it already inspects the variadic
parameter's element type, not "array", per PHP reflection semantics)
and appends to the result in order; variadic is always the last
parameter, so this preserves correct positional ordering. A non-array
value for a variadic argument now fails clearly with an invalid-params
error instead of the confusing cast message.
* Address chr-hertel's review: wrap scalars, reject objects, index cast errors
- Non-array variadic argument is now wrapped as a single-element list
instead of being rejected: MCP prompt arguments are always
Record<string,string> per protocol, so a variadic prompt parameter
legitimately receives a plain string, not an array. Rejecting it
regressed behaviour that worked on main.
- A JSON object (non-list array) is now explicitly rejected instead of
being silently flattened into positional args by array_values().
- Cast-failure errors now include the parameter name and element index,
so a failure inside a large array is actually actionable.
- Trimmed the inline rationale comment; the PR description already
covers it.
Tests updated: replaced the "throws on non-array" test (no longer
correct) with tests for the wrap-as-single-element, reject-object, and
indexed-error-message behaviours.
* Pin argument order for an injectable before a variadic
---------
Co-authored-by: Christopher Hertel <mail@christopher-hertel.de>
46628fbe6a