Add an option to add extra metadata that is pushed and passed to Guardrails during an MCP session (#47)

* use select() before readline

* support for setting static metadata for MCP sessions

* nest extra mcp metadata in metadata object

* unify session metadata

* extra metadata tests

* use empty object as parameters, if None

* list_tools as tool call

* offset indices in tests

* test: adjust addresses

* mcp: make error reporting configurable

* line logging

* log version

* verbose logging + loud exception failure

* add server and client name to policy get

* append trace even if not pushing

* port tools/list message support to SSE

* use python -m build

* adjust guardrail failure address

* support for blocking tools/list in SSE

* use error-based failure response format by default

* tools/list test

* don't list_tools in stdio connect

* flaky test: handle second possible result in anthropic streaming case

---------

Co-authored-by: knielsen404 <kristian@invariantlabs.ai>

tests/integration/resources/mcp/sse/client/main.py

@@ -97,7 +97,13 @@ async def run(
                 "PUSH-INVARIANT-EXPLORER": str(push_to_explorer),
             },
         )
-        return await client.process_query(tool_name, tool_args)
+        # list tools
+        listed_tools = await client.session.list_tools()
+        # call tool
+        if tool_name == "tools/list":
+            return listed_tools
+        else:
+            return await client.process_query(tool_name, tool_args)
     finally:
         # Sleep for a while to allow the server to process the background tasks
         # like pushing traces to the explorer

tests/integration/resources/mcp/stdio/client/main.py

@@ -23,6 +23,7 @@ class MCPClient:
         project_name: str,
         server_script_path: str,
         push_to_explorer: bool,
+        metadata_keys: Optional[dict[str, str]] = None,
     ):
         """
         Connect to an MCP server.
@@ -42,6 +43,12 @@ class MCPClient:
             "--project-name",
             project_name,
         ]
+        # add metadata cli args
+        if metadata_keys is not None:
+            for key, value in metadata_keys.items():
+                args.append("--metadata-" + key + "=" + value)
+
+
         if push_to_explorer:
             args.append("--push-explorer")
         args.extend(
@@ -54,6 +61,7 @@ class MCPClient:
                 os.path.basename(server_script_path),
             ]
         )
+
         server_params = StdioServerParameters(
             command="uvx",
             args=args,
@@ -73,6 +81,7 @@ class MCPClient:
             )
         )
 
+        # initialize the session
         await self.session.initialize()
 
     async def call_tool(
@@ -101,6 +110,7 @@ async def run(
     push_to_explorer: bool,
     tool_name: str,
     tool_args: dict[str, Any],
+    metadata_keys: Optional[dict[str, str]] = None,
 ) -> types.CallToolResult:
     """
     Main function to setup the MCP client and server.
@@ -123,7 +133,13 @@ async def run(
             project_name,
             server_script_path,
             push_to_explorer,
+            metadata_keys=metadata_keys
         )
-        return await client.call_tool(tool_name, tool_args)
+        listed_tools = await client.session.list_tools()
+        if tool_name == "tools/list":
+            # list tools
+            return listed_tools
+        else:
+            return await client.call_tool(tool_name, tool_args)
     finally:
         await client.cleanup()