Return `CallToolResult` from `convert_result` instead of a tuple #959

Job	Run time
checks / readme-snippets	16s
checks / pre-commit	37s
checks / test (3.11, lowest-direct, ubuntu-latest)	55s
checks / test (3.10, lowest-direct, windows-latest)	3m 5s
checks / test (3.11, lowest-direct, windows-latest)	2m 37s
checks / test (3.10, lowest-direct, ubuntu-latest)	55s
checks / test (3.10, locked, windows-latest)	2m 21s
checks / test (3.14, lowest-direct, ubuntu-latest)	1m 20s
checks / test (3.11, locked, windows-latest)	2m 46s
checks / test (3.11, locked, ubuntu-latest)	49s
checks / test (3.12, locked, windows-latest)	3m 17s
checks / test (3.14, lowest-direct, windows-latest)	3m 5s
checks / test (3.12, lowest-direct, windows-latest)	3m 39s
checks / test (3.12, locked, ubuntu-latest)	53s
checks / test (3.13, lowest-direct, windows-latest)	2m 33s
checks / test (3.12, lowest-direct, ubuntu-latest)	59s
checks / test (3.13, lowest-direct, ubuntu-latest)	56s
checks / test (3.13, locked, windows-latest)	2m 32s
checks / test (3.14, locked, windows-latest)	3m 1s
checks / test (3.14, locked, ubuntu-latest)	2m 17s
checks / test (3.13, locked, ubuntu-latest)	40s
checks / test (3.10, locked, ubuntu-latest)	53s
all-green	2s
	40m 28s

Provide feedback