[Schema] Always emit {} for empty tool schema properties - #407
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Normalize empty properties arrays (including nested object schemas and outputSchema) in Tool::__construct so tools/list never serializes invalid JSON Schema properties: []. Fixes modelcontextprotocol#405
BrocksiNet
requested review from
CodeWithKyrian,
Nyholm,
chr-hertel and
soyuka
as code owners
July 28, 2026 11:44
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Summary
propertiesnormalization intoTool::__construct()so every construction path (not onlyfromArray/SchemaGenerator) emits JSON Schema objects as{}instead of[].items,additionalProperties, and combinators, and apply it tooutputSchemaas well.json_decoderound-trips, nested objects, array item schemas, and emptyoutputSchema.properties.Fixes #405
Test plan
make unit-tests(834 tests)make phpstanmake csmake inspector-tests(95 tests, 7 skipped)composer validate --strict"properties":{}intools/listagainst a strict client (e.g. OpenAI-compatible)