fix(mcpserver): advertise capabilities only for registered primitives #2196

Job	Run time
checks / readme-snippets	14s
checks / pre-commit	34s
checks / test (3.11, lowest-direct, ubuntu-latest)	57s
checks / test (3.10, locked, windows-latest)	2m 51s
checks / test (3.10, lowest-direct, ubuntu-latest)	56s
checks / test (3.10, locked, ubuntu-latest)	53s
checks / test (3.11, locked, windows-latest)	2m 31s
checks / test (3.13, lowest-direct, ubuntu-latest)	54s
checks / test (3.11, lowest-direct, windows-latest)	2m 54s
checks / test (3.12, lowest-direct, ubuntu-latest)	1m 5s
checks / test (3.13, locked, windows-latest)	2m 11s
checks / test (3.12, locked, ubuntu-latest)	56s
checks / test (3.10, lowest-direct, windows-latest)	2m 42s
checks / test (3.13, lowest-direct, windows-latest)	3m 54s
checks / test (3.14, locked, ubuntu-latest)	2m 20s
checks / test (3.14, lowest-direct, ubuntu-latest)	1m 16s
checks / test (3.13, locked, ubuntu-latest)	44s
checks / test (3.14, lowest-direct, windows-latest)	2m 13s
checks / test (3.11, locked, ubuntu-latest)	56s
checks / test (3.12, lowest-direct, windows-latest)	3m 41s
checks / test (3.14, locked, windows-latest)	3m 49s
checks / test (3.12, locked, windows-latest)	3m 28s
all-green	5s
	42m 4s

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