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Python: MCP tools with execution.taskSupport "optional" are skipped, although they can be called without Tasks #9675
Description
Versions: agent-framework 1.23.0, agent-framework-foundry-hosting 1.0.0b261022, mcp 2.3.0 (worked in agent-framework 1.21.0 with mcp 1.x).
What happens
Since the MCP 2.x migration (#9236), _load_tools_locked skips every tool whose execution.taskSupport is "required" or "optional":
Skipping MCP tool 'pbi-mcp___ExecuteQuery' because it (might) require the Tasks extension, which MCP Python SDK 2.2 does not implement.
A Foundry Toolbox (FoundryToolbox) marks its Power BI MCP tools and its Foundry IQ knowledge-base tool as "optional". After upgrading from 1.21 to 1.23, all of them disappear from the agent; only tools without taskSupport remain.
Expected
Per the MCP spec, "optional" means the client may invoke the tool with task augmentation, but a plain tools/call is valid. Only "required" tools need the Tasks extension. With 1.21 / mcp 1.x the same tools were called normally and work.
Suggestion
Skip only "required", and call "optional" tools as plain calls until Tasks client support (#9215) lands. Alternatively, make this configurable on MCPStreamableHTTPTool / FoundryToolbox.
Impact
Blocks upgrading Foundry-hosted agents that use Toolbox connections, with no workaround short of patching internals.
Activity
Sainath-Reddy7 commentedon Oct 25, 2026
Reproduced on agent-framework-core 1.23.0 + mcp 2.3.0 — thanks for the clear report.
Minimal repro (mirroring the mock-session pattern from
tests/core/test_mcp.py): a session exposing two tools, one plain and one withexecution.task_support="optional", producesand only the plain tool ends up in
tool._functions.Root cause is the membership test at
python/packages/core/agent_framework/_mcp.py(~line 3110):if task_support in ["required", "optional"]skips both. Per the Tasks-extension semantics,"optional"means the tool works without the extension (it may use it when available), so only"required"warrants skipping — which would also let the warning message drop the "(might)" hedge.Proposed direction: skip only when
task_support == "required", load"optional"tools normally, and add a regression test with both variants.Following the AI-assisted contributions policy: this analysis and repro were prepared with an AI coding agent at my direction and reviewed by me; happy to implement once a maintainer adds
ready-for-implementationor agrees with the direction.