fix(cli): update graph config schema to support description field (#6895)

## Summary
- The config processing code in `config.py` already handles graphs
defined as `{"path": "...", "description": "..."}` dicts, but the
`Config` TypedDict and JSON schema only declared `dict[str, str]`
- Added a `GraphDef` TypedDict with `path` and optional `description`
fields
- Updated `Config.graphs` to `dict[str, str | GraphDef]` and regenerated
the JSON schemas
- This makes the schema match the actual runtime behavior and fixes
IDE/schema validation for users who use the dict format

## Test plan
- [x] `make format` passes
- [x] `make lint` passes
- [x] `make test` passes (all 85 tests)
- [x] Schema regeneration produces consistent output

Release Notes: Update `langgraph.json` schema to support `{"path":
"...", "description": "..."}` format for graph definitions.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

libs/cli/langgraph_cli/schemas.py

@@ -529,6 +529,21 @@ class WebhookUrlPolicy(TypedDict, total=False):
     """Disallow relative URLs (internal loopback calls) when true."""
 
 
+class GraphDef(TypedDict, total=False):
+    """Definition of a graph with additional metadata."""
+
+    path: str
+    """Required. Import path to the graph object.
+
+    Format: "path/to/file.py:object_name"
+    """
+    description: str | None
+    """Optional. A description of the graph's purpose and functionality.
+
+    This description is surfaced in the API and can help users understand what the graph does.
+    """
+
+
 class WebhooksConfig(TypedDict, total=False):
     env_prefix: str
     """Required prefix for environment variables referenced in header templates.
@@ -619,19 +634,23 @@ class Config(TypedDict, total=False):
     Defaults to an empty list, meaning no additional packages installed beyond your base environment.
     """
 
-    graphs: dict[str, str]
+    graphs: dict[str, str | GraphDef]
     """Optional. Named definitions of graphs, each pointing to a Python object.
 
-    
+
     Graphs can be StateGraph, @entrypoint, or any other Pregel object OR they can point to (async) context
     managers that accept a single configuration argument (of type RunnableConfig) and return a pregel object
     (instance of Stategraph, etc.).
-    
-    Keys are graph names, values are "path/to/file.py:object_name".
+
+    Keys are graph names, values are either "path/to/file.py:object_name" strings
+    or objects with a "path" key and optional "description" key.
     Example:
         {
             "mygraph": "graphs/my_graph.py:graph_definition",
-            "anothergraph": "graphs/another.py:get_graph"
+            "anothergraph": {
+                "path": "graphs/another.py:get_graph",
+                "description": "A graph that does X"
+            }
         }
     """
 
@@ -696,6 +715,7 @@ class Config(TypedDict, total=False):
 
 __all__ = [
     "Config",
+    "GraphDef",
     "StoreConfig",
     "CheckpointerConfig",
     "AuthConfig",