fix #181: improve MCP tool descriptions — remove filler text, add meaningful parameter docs (#193)

- Remove 'Use when you need this data from Bloomreach project workflows' filler from 77 browser-only tools
- Replace 'Returns { error: string }' error notes with '⚠️ Not yet available — coming in a future release'
- Remove 'Use when you need live data from Bloomreach Engagement APIs' filler from 14 API-backed tools
- Rewrite 154 prepare_* descriptions: replace generic two-phase commit boilerplate with action-specific descriptions
- Improve 117 parameter descriptions: replace 'Identifier for the target resource (X)' with contextual descriptions referencing list tools
- Replace 39 generic 'Human-readable name for the resource being created' with resource-specific descriptions
- Replace 5 generic 'Configuration payload for the target resource' with contextual descriptions

Author: sigvardt