One-shot CLI cannot call a legacy tool with taskSupport: "required" #2649

Problem

Found during the v2.10.0 release smoke (#2623) and recorded in its ledger. The behavior predates 2.9.0. Against a legacy-era server whose tool declares taskSupport: "required", the one-shot CLI fails:

Tool "simple_task" requires task support. Use callToolStream() instead of callTool().

It exits 1. mcpdo can call the same tool with tools/call --task; without --task it fails the same way. The CLI has no equivalent flag and never takes the streaming path.

Reproduce

node test-servers/build/server-composable.js --config test-servers/configs/tasks-legacy-http.json   # note its port
mcp-inspector --cli --server-url http://127.0.0.1:<port>/mcp --transport http --method tools/call --tool-name simple_task

Expected

The CLI can call a task-required tool, either automatically (use the task path when the tool requires it) or through a --task flag matching mcpdo, and it prints the task's result.

Priority

Medium (rubric total 6): Severity 3 (a real tool cannot be called from the CLI; mcpdo is the workaround), Urgency 1, +1 bug, +1 milestoned.