fix(mcp): extract and elevate struct docstrings into root tool schema descriptions to restore semantic LLM visibility

server/src/mcp.rs

@@ -20,13 +20,19 @@ pub fn error(id: serde_json::Value, code: i32, message: &str) -> serde_json::Val
     })
 }
 
-pub fn tool_def<T: JsonSchema>(name: &str, description: &str) -> serde_json::Value {
+pub fn tool_def<T: JsonSchema>(name: &str, fallback_desc: &str) -> serde_json::Value {
     let schema = schemars::schema_for!(T);
     let schema_val = serde_json::to_value(&schema).unwrap_or_default();
+    
+    let desc = schema_val.get("description")
+        .and_then(|d| d.as_str())
+        .unwrap_or(fallback_desc)
+        .to_string();
+
     // MCP expects standard JSON schema. Schemars returns draft-07.
     json!({
         "name": name,
-        "description": description,
+        "description": desc,
         "inputSchema": schema_val
     })
 }

server/src/tools.rs

@@ -55,7 +55,7 @@ pub struct DeleteRelationsTool {
     pub relations: Vec<crate::models::Relation>,
 }
 
-/// Read the entire knowledge graph.
+/// Read the entire knowledge graph. WARNING: For large graphs, use search_nodes instead to avoid context limits.
 #[derive(Debug, Deserialize, Serialize, JsonSchema)]
 pub struct ReadGraphTool {
     /// Optional namespace to restrict the read to.