Add standard `readOnlyHint` / `destructiveHint` annotations on tools for native client grouping

[bst1n]

Context

PR #110 (closes #70) added ghst/toolGroup and ghst/toolGroupTitle metadata in the _meta field of each tool. This was a forward-looking choice anticipating future MCP grouping standards.

However, this custom namespace isn't recognized by any current MCP client (including Claude Desktop), so all 91 tools still appear as a flat "Other tools" list in the client UI.

What clients actually use today

Claude Desktop renders tool groups based on the MCP standard annotations readOnlyHint and destructiveHint. As an example, the Airtable connector groups its tools into "Read-only tools" (12) and "Write/Delete tools" (9) automatically because each tool carries the appropriate annotation.

State of custom-category grouping in the MCP spec

• SEP-1300 (Tool Filtering with Groups and Tags) was rejected.
• The active follow-up is Discussion #1772 (Use Cases for Grouping of Tools, Prompts, Resources) — still open, last activity March 2026.
• A community implementation is now available across SDKs as OpenMCPTools/toolgroups (Python, TypeScript, Java) — it's the closest thing to a forming standard.

So custom-category grouping (Posts / Pages / Stats / etc.) isn't supported by clients today and isn't in the spec — it might land via the toolgroups extension or a future SEP, but there's no ETA.

Suggestion

Complement the existing ghst/toolGroup metadata (keep it — it's good future-proofing) by adding the standard annotations.readOnlyHint and annotations.destructiveHint fields on each tool. This would give immediate visible grouping in Claude Desktop and other compliant clients, without removing any existing capability.

Examples:

• ghost_post_list, ghost_post_get, ghost_stats_* → readOnlyHint: true
• ghost_post_delete, ghost_member_delete → destructiveHint: true
• ghost_post_create, ghost_post_update → neither hint (write but non-destructive)