fix: correct unknown tool/prompt/resource error handling #920

Job	Run time
checks / pre-commit	34s
checks / readme-snippets	13s
checks / test (3.10, locked, ubuntu-latest)	50s
checks / test (3.12, lowest-direct, windows-latest)	3m 47s
checks / test (3.10, lowest-direct, ubuntu-latest)	57s
checks / test (3.11, lowest-direct, ubuntu-latest)	1m 1s
checks / test (3.12, lowest-direct, ubuntu-latest)	57s
checks / test (3.11, locked, ubuntu-latest)	49s
checks / test (3.10, locked, windows-latest)	2m 14s
checks / test (3.14, lowest-direct, ubuntu-latest)	1m 21s
checks / test (3.10, lowest-direct, windows-latest)	2m 34s
checks / test (3.11, locked, windows-latest)	2m 36s
checks / test (3.13, lowest-direct, windows-latest)	2m 35s
checks / test (3.14, lowest-direct, windows-latest)	2m 12s
checks / test (3.12, locked, ubuntu-latest)	55s
checks / test (3.13, locked, ubuntu-latest)	49s
checks / test (3.13, lowest-direct, ubuntu-latest)	51s
checks / test (3.12, locked, windows-latest)	3m 25s
checks / test (3.14, locked, windows-latest)	3m 8s
checks / test (3.11, lowest-direct, windows-latest)	2m 47s
checks / test (3.14, locked, ubuntu-latest)	2m 38s
checks / test (3.13, locked, windows-latest)	2m 36s
all-green	4s
	39m 53s

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