fix(google-analytics): fix input validation and align output schemas

[yuriassuncx]

Summary

• Fix input validation errors — some MCP clients (e.g. Claude Desktop, third-party hosts) serialize array and object parameters as JSON strings instead of native types. Added a fromJson preprocessor (z.preprocess) in reports.ts that transparently parses JSON strings before Zod validation. This fixes all 6 reported errors: dateRanges, dimensions, metrics, dimensionFilter, metricFilter, orderBys, orderBys, limit, and offset.
• Remove { response: ... } wrapper from all output schemas — all tools now return data directly (e.g. { rows: [...] } instead of { response: { rows: [...] } }), consistent with google-search-console and google-tag-manager patterns.
• Flatten getCustomDimensionsAndMetrics output — from { dimensions: { customDimensions: [...] }, metrics: { customMetrics: [...] } } to { customDimensions: [...], customMetrics: [...] }.
• Fix code formatting — remove unnecessary blank lines between chained Zod method calls across all tool files.

Root cause

The validation error was:
```
Invalid input: expected array, received string (dateRanges, dimensions, metrics, orderBys)
Invalid input: expected record, received string (dimensionFilter)
Invalid input: expected number, received string (limit)
```

The fix uses z.preprocess to attempt JSON.parse on string inputs before Zod validates them. If parsing fails, the original value is passed through and Zod produces a clear type error.

Test plan

• Run run-report with native JSON arrays — should work as before
• Run run-report with JSON-stringified arrays — should now pass validation
• Verify get-account-summaries output is now { accountSummaries: [...] } (no response wrapper)
• Verify run-report output is now { rows: [...], dimensionHeaders: [...], ... } (no response wrapper)
• Verify get-custom-dimensions-and-metrics output is { customDimensions: [...], customMetrics: [...] } (flat)

🤖 Generated with Claude Code

---

Summary by cubic

Fixes GA4 tool input validation across MCP clients (handles JSON‑stringified arrays/objects/booleans and both "null" strings and native nulls) and updates all outputs to return top‑level data without a response wrapper, matching google-search-console and google-tag-manager. Also flattens the custom dimensions/metrics output.

• Bug Fixes

  • Parse JSON‑stringified arrays/objects/booleans and coerce "null" and native null to undefined before validation.
  • Handles: dateRanges, dimensions, metrics, dimensionFilter, metricFilter, orderBys, limit, offset, funnelSteps, returnPropertyQuota, isDirectlyFollowedBy.

• Migration

  • All tools now return data directly (no { response: ... }). Remove response. from callers.
  • getCustomDimensionsAndMetrics now returns { customDimensions, customMetrics }.
  • Affected tools: accounts, properties, ads links, annotations, runReport, runRealtimeReport, runFunnelReport.

^{Written for commit fd42de0. Summary will update on new commits.}