(superset) 01/01: docs(mcp): document chart type plugin filtering config

[ru...@apache.org]

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rusackas pushed a commit to branch fix/from-pr-39922-needs-docs-feat-mcp-chart-type-plugin-re
in repository https://gitbox.apache.org/repos/asf/superset.git

commit bc059c3f9bd986176d1e5e580790b35f7e6d765c
Author: rusackas <ev...@rusackas.com>
AuthorDate: Thu Aug 27 08:54:39 2026 -0700

    docs(mcp): document chart type plugin filtering config
    
    MCP_DISABLED_CHART_PLUGINS and MCP_CHART_PLUGIN_ENABLED_FUNC (added in
    support of the chart-type plugin registry in #39922) let operators
    deny-list or dynamically gate individual chart type plugins in
    generate_chart, but weren't documented in the MCP server config
    reference.
    
    Co-Authored-By: Claude <no...@anthropic.com>
---
 docs/admin_docs/configuration/mcp-server.mdx | 35 ++++++++++++++++++++++++++++
 1 file changed, 35 insertions(+)

diff --git a/docs/admin_docs/configuration/mcp-server.mdx b/docs/admin_docs/configuration/mcp-server.mdx
index c6e6acd4656..0ca12fccc16 100644
--- a/docs/admin_docs/configuration/mcp-server.mdx
+++ b/docs/admin_docs/configuration/mcp-server.mdx
@@ -505,6 +505,8 @@ All MCP settings go in `superset_config.py`. Defaults are defined in `superset/m
 | `MCP_DEV_USERNAME`   | --            | Superset username for development mode (no auth)                                                                                                                                                                                                                             |
 | `MCP_RBAC_ENABLED`   | `True`        | Enforce Superset's role-based access control on MCP tool calls. When `True`, each tool checks that the authenticated user has the required FAB permission before executing. Disable only for testing or trusted-network deployments.                                         |
 | `MCP_DISABLED_TOOLS` | `set()`       | Set of tool names to remove from the MCP server at startup. Disabled tools are never advertised to AI clients during tool discovery. Useful when a custom extension tool should replace a built-in Superset tool. See [Disabling built-in tools](#disabling-built-in-tools). |
+| `MCP_DISABLED_CHART_PLUGINS` | `frozenset()` | Set of chart type plugin names (e.g. `"handlebars"`) to hide from `generate_chart` and related chart tools. See [Disabling chart type plugins](#disabling-chart-type-plugins). |
+| `MCP_CHART_PLUGIN_ENABLED_FUNC` | `None`        | Callable `(chart_type: str) -> bool` evaluated per registry lookup for dynamic enable/disable decisions. Takes precedence over `MCP_DISABLED_CHART_PLUGINS` when set. See [Disabling chart type plugins](#disabling-chart-type-plugins). |
 
 ### Authentication
 
@@ -893,6 +895,39 @@ MCP_DISABLED_TOOLS = {"extensions.myorg.myextension.some_tool"}
 Specifying a tool name that does not exist logs a warning at startup and is otherwise ignored — it will not prevent the server from starting.
 :::
 
+## Disabling chart type plugins
+
+The `generate_chart` tool dispatches per chart type (`xy`, `table`, `pie`, `pivot_table`, `mixed_timeseries`, `handlebars`, `big_number`) to a registered chart type plugin. Two settings let operators enable or disable individual chart type plugins at runtime, without a code deploy.
+
+### Static deny-list
+
+Set `MCP_DISABLED_CHART_PLUGINS` in your `superset_config.py` to a set of chart type names:
+
+```python
+# superset_config.py
+
+# Emergency kill switch: hide "handlebars" from all callers
+MCP_DISABLED_CHART_PLUGINS = {"handlebars"}
+```
+
+Disabled chart types are removed from the registry at startup and are never listed in `generate_chart`'s supported chart types.
+
+### Dynamic predicate
+
+For per-request control (A/B tests, gradual rollout, entitlement checks), set `MCP_CHART_PLUGIN_ENABLED_FUNC` to a callable. It's evaluated as `enabled_func(chart_type: str) -> bool` on every registry lookup, and it takes precedence over `MCP_DISABLED_CHART_PLUGINS` when set:
+
+```python
+# superset_config.py
+from flask import g
+
+
+def MCP_CHART_PLUGIN_ENABLED_FUNC(chart_type: str) -> bool:
+    flags = getattr(g, "feature_flags", {})
+    return flags.get(f"mcp_chart_{chart_type}", True)
+```
+
+The callable must be cheap and in-process (consult already-loaded feature flags or request-local context) -- do not perform network I/O per call. If it raises, the registry fails closed (the plugin is hidden) and logs a warning.
+
 ## Security Best Practices
 
 - **Use TLS** for all production MCP endpoints -- place the server behind a reverse proxy with HTTPS