aminghadersohi opened a new pull request, #38532:
URL: https://github.com/apache/superset/pull/38532
### SUMMARY
Fixes three issues with MCP tool calls reported when using external MCP
clients (Grok, etc.):
1. **`open_sql_lab_with_context` returned relative URLs** (`/sqllab?...`)
while every other tool returns absolute URLs via `get_superset_base_url()`.
This forced LLMs to guess the base URL, leading to hallucinated `{{
preset_base_url }}` template syntax or broken links.
2. **LLMs fabricate URLs** instead of calling chart tools — the
`DEFAULT_INSTRUCTIONS` lacked explicit guardrails telling LLMs to never invent
URLs and always use tool results.
3. **LLMs call `execute_sql` instead of `update_chart`** when asked to
modify chart filters — the instructions didn't include a "modify an existing
chart" workflow or parameter name reminders.
**Changes:**
- `open_sql_lab_with_context.py`: Import `get_superset_base_url` and use it
to construct absolute SQL Lab URLs, matching the pattern used by
`generate_chart`, `generate_dashboard`, `add_chart_to_existing_dashboard`, etc.
- `app.py` (`DEFAULT_INSTRUCTIONS`): Add anti-hallucination guardrails
(never fabricate URLs, use `update_chart` for chart modifications, correct
parameter names) and a "modify an existing chart" workflow section.
### BEFORE/AFTER SCREENSHOTS OR ANIMATED GIF
N/A — backend-only change to MCP tool output and instructions text.
### TESTING INSTRUCTIONS
1. Connect an MCP client (e.g., Claude Desktop, Grok) to the Superset MCP
service
2. Ask the chatbot to "open SQL Lab for database X" — verify the returned
URL is absolute (starts with `http://...`) not relative (`/sqllab?...`)
3. Ask "add a filter to chart 123" — verify it uses `update_chart`, not
`execute_sql`
4. Ask "show me a chart of sales data" — verify it calls
`generate_explore_link` or `generate_chart` instead of fabricating a URL
### ADDITIONAL INFORMATION
- [ ] Has associated issue:
- [ ] Required feature flags:
- [ ] Changes UI
- [ ] Includes DB Migration (follow approval process in
[SIP-59](https://github.com/apache/superset/issues/13351))
- [ ] Migration is atomic, supports rollback & is backwards-compatible
- [ ] Confirm DB migration upgrade and downgrade tested
- [ ] Runtime estimates and downtime expectations provided
- [ ] Introduces new feature or API
- [ ] Removes existing feature or API
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