As per bug #562 I'm also getting these exceptions when running the latest 0.14.0 in repo (not deployed yet).

java.lang.IllegalStateException: No default JsonSchemaValidatorSupplier implementation found
at io.modelcontextprotocol.json.schema.JsonSchemaInternal.lambda$createDefaultValidator$2(JsonSchemaInternal.java:66)
at java.base/java.util.Optional.orElseThrow(Optional.java:403)
at io.modelcontextprotocol.json.schema.JsonSchemaInternal.createDefaultValidator(JsonSchemaInternal.java:61)
at io.modelcontextprotocol.json.schema.JsonSchemaInternal.getDefaultValidator(JsonSchemaInternal.java:30)
at io.modelcontextprotocol.json.schema.JsonSchemaValidator.getDefault(JsonSchemaValidator.java:61)
at io.modelcontextprotocol.server.McpServer$SingleSessionAsyncSpecification.build(McpServer.java:232)
at ...

and

java.lang.IllegalStateException: No default McpJsonMapper implementation found
at io.modelcontextprotocol.json.McpJsonInternal.lambda$createDefaultMapper$2(McpJsonInternal.java:67)
at java.base/java.util.Optional.orElseThrow(Optional.java:403)
at io.modelcontextprotocol.json.McpJsonInternal.createDefaultMapper(McpJsonInternal.java:62)
at io.modelcontextprotocol.json.McpJsonInternal.getDefaultMapper(McpJsonInternal.java:30)
at io.modelcontextprotocol.json.McpJsonMapper.getDefault(McpJsonMapper.java:97)
at io.modelcontextprotocol.server.McpServer$SingleSessionSyncSpecification.build(McpServer.java:818)
at ...

This problem does not appear to me to be an OSGi problem as when I look in the mcp-json project there does not appear to be any META-INF/services/* files. I can see that the ServiceLoader is used in io.modelcontextprotocol.json.schema.JsonSchemaInternal line 41, and in io.modelcontextprotocol.json.McpJsonInternal line 45, so I suspect that the META-INF/services/* files in mcp-json were accidently not checked in.