New Features (2026-06-19) — MCP Structured Tool Output

The MCP server now supports the 2025-06-18 structured tool output spec feature: a tool may declare an outputSchema, and its dict result is returned as structuredContent in the tools/call response (alongside the usual text content). MCP clients and LLMs can then consume a typed, schema-validated object instead of re-parsing text — saving tokens and errors. Pure standard library; an MCP-framework enhancement (no new AC_* command).

Declaring an output schema

from je_auto_control.utils.mcp_server.tools import MCPTool

MCPTool(
    name="ac_validate_rows", description="...",
    input_schema=..., handler=validate_rows,
    output_schema={"type": "object", "properties": {
        "ok": {"type": "boolean"}, "errors": {"type": "array"}}},
)

to_descriptor() then includes outputSchema in tools/list, and a tools/call whose handler returns a dict includes structuredContent in the result. Tools without an outputSchema are unchanged; non-dict results never produce structuredContent.

The first built-in tool to adopt this is ac_validate_rows (data-quality validation), whose {ok, total, valid_count, invalid_count, errors, ...} result is now schema-typed; more tools can opt in by adding an output_schema.