MCP server: 100+ tools, JSON-RPC and SSE

Added

• 100+ MCP tools across accounts, audits, campaigns, keywords, budgets, bidding, audiences, reporting, recommendations, automation and Meta.
• JSON-RPC 2.0 endpoint at POST /api/v1/mcp with initialize, tools/list and tools/call.
• Server-Sent Events transport for clients that require it.
• Per-account, per-scope API keys.

Improved

• Mutating tools now return a change id that links to the audit trail.