internal/mcp: disable schema validation

Schema validation is causing breakage for some usage inide of Google.
While this may be a downstream bug, it is blocking the import of x/tools
into Google. Disable it for now, to unblock the import.

No tests failed when schema validation is removed. We need to add more
tests before re-enabling this feature.

Change-Id: I72905a93bfb0a2d81bae467d903f027e71719487
Reviewed-on: https://go-review.googlesource.com/c/tools/+/684935
Reviewed-by: Jonathan Amsterdam <[email protected]>
LUCI-TryBot-Result: Go LUCI <[email protected]>

Author: findleyr

internal/mcp/server.go

@@ -19,7 +19,6 @@ import (
 
 	jsonrpc2 "golang.org/x/tools/internal/jsonrpc2_v2"
 	"golang.org/x/tools/internal/mcp/internal/util"
-	"golang.org/x/tools/internal/mcp/jsonschema"
 )
 
 const DefaultPageSize = 1000
@@ -138,13 +137,14 @@ func (s *Server) addToolsErr(tools ...*ServerTool) error {
 			st.rawHandler = newRawHandler(st)
 			// Resolve the schemas, with no base URI. We don't expect tool schemas to
 			// refer outside of themselves.
-			if st.Tool.InputSchema != nil {
-				r, err := st.Tool.InputSchema.Resolve(&jsonschema.ResolveOptions{ValidateDefaults: true})
-				if err != nil {
-					return err
-				}
-				st.inputResolved = r
-			}
+			// TODO(rfindley): re-enable schema validation. See note in [ServerTool].
+			// if st.Tool.InputSchema != nil {
+			// 	r, err := st.Tool.InputSchema.Resolve(&jsonschema.ResolveOptions{ValidateDefaults: true})
+			// 	if err != nil {
+			// 		return err
+			// 	}
+			// 	st.inputResolved = r
+			// }
 
 			// TODO: uncomment when output schemas drop.
 			// if st.Tool.OutputSchema != nil {

internal/mcp/tool.go

@@ -33,7 +33,8 @@ type ServerTool struct {
 	// Set in NewServerTool or Server.AddToolsErr.
 	rawHandler rawToolHandler
 	// Resolved tool schemas. Set in Server.AddToolsErr.
-	inputResolved, outputResolved *jsonschema.Resolved
+	// TODO(rfindley): re-enable schema validation. For now, it is causing breakage in Google.
+	// inputResolved, outputResolved *jsonschema.Resolved
 }
 
 // NewServerTool is a helper to make a tool using reflection on the given type parameters.
@@ -79,7 +80,8 @@ func newServerToolErr[In, Out any](name, description string, handler ToolHandler
 	t.rawHandler = func(ctx context.Context, ss *ServerSession, rparams *CallToolParamsFor[json.RawMessage]) (*CallToolResult, error) {
 		var args In
 		if rparams.Arguments != nil {
-			if err := unmarshalSchema(rparams.Arguments, t.inputResolved, &args); err != nil {
+			// TODO(rfindley): re-enable schema validation. See note in [ServerTool].
+			if err := unmarshalSchema(rparams.Arguments, nil, &args); err != nil {
 				return nil, err
 			}
 		}
@@ -117,7 +119,8 @@ func newRawHandler(st *ServerTool) rawToolHandler {
 		// Unmarshal the args into what should be a map.
 		var args map[string]any
 		if rparams.Arguments != nil {
-			if err := unmarshalSchema(rparams.Arguments, st.inputResolved, &args); err != nil {
+			// TODO(rfindley): re-enable schema validation. See note in [ServerTool].
+			if err := unmarshalSchema(rparams.Arguments, nil, &args); err != nil {
 				return nil, err
 			}
 		}