fix: various fixes for openapi support (#208)

Signed-off-by: Grant Linville <grant@acorn.io>

Author: g-linville

pkg/loader/loader.go

@@ -131,7 +131,11 @@ func readTool(ctx context.Context, prg *types.Program, base *source, targetToolN
 	var tools []types.Tool
 	if isOpenAPI(data) {
 		if t, err := openapi3.NewLoader().LoadFromData(data); err == nil {
-			tools, err = getOpenAPITools(t)
+			if base.Remote {
+				tools, err = getOpenAPITools(t, base.Location)
+			} else {
+				tools, err = getOpenAPITools(t, "")
+			}
 			if err != nil {
 				return types.Tool{}, fmt.Errorf("error parsing OpenAPI definition: %w", err)
 			}
@@ -256,6 +260,9 @@ func ProgramFromSource(ctx context.Context, content, subToolName string) (types.
 }
 
 func Program(ctx context.Context, name, subToolName string) (types.Program, error) {
+	if subToolName == "" {
+		name, subToolName = SplitToolRef(name)
+	}
 	prg := types.Program{
 		Name:    name,
 		ToolSet: types.ToolSet{},
@@ -306,7 +313,7 @@ func input(ctx context.Context, base *source, name string) (*source, error) {
 }
 
 func SplitToolRef(targetToolName string) (toolName, subTool string) {
-	subTool, toolName, ok := strings.Cut(targetToolName, " from ")
+	subTool, toolName, ok := strings.Cut(strings.ReplaceAll(targetToolName, "\t", " "), " from ")
 	if ok {
 		toolName = strings.TrimSpace(toolName)
 		subTool = strings.TrimSpace(subTool)
@@ -318,14 +325,14 @@ func SplitToolRef(targetToolName string) (toolName, subTool string) {
 }
 
 func isOpenAPI(data []byte) bool {
-	var version struct {
-		OpenAPI string `json:"openapi" yaml:"openapi"`
+	var fragment struct {
+		Paths map[string]any `json:"paths,omitempty"`
 	}
 
-	if err := json.Unmarshal(data, &version); err != nil {
-		if err := yaml.Unmarshal(data, &version); err != nil {
+	if err := json.Unmarshal(data, &fragment); err != nil {
+		if err := yaml.Unmarshal(data, &fragment); err != nil {
 			return false
 		}
 	}
-	return strings.HasPrefix(version.OpenAPI, "3.")
+	return len(fragment.Paths) > 0
 }

pkg/loader/openapi.go

@@ -3,6 +3,7 @@ package loader
 import (
 	"encoding/json"
 	"fmt"
+	"net/url"
 	"slices"
 	"strings"
 
@@ -15,9 +16,19 @@ import (
 // Each operation will become a tool definition.
 // The tool's Instructions will be in the format "#!sys.openapi '{JSON Instructions}'",
 // where the JSON Instructions are a JSON-serialized engine.OpenAPIInstructions struct.
-func getOpenAPITools(t *openapi3.T) ([]types.Tool, error) {
+func getOpenAPITools(t *openapi3.T, defaultHost string) ([]types.Tool, error) {
+	// Determine the default server.
 	if len(t.Servers) == 0 {
-		return nil, fmt.Errorf("no servers found in OpenAPI spec")
+		if defaultHost != "" {
+			u, err := url.Parse(defaultHost)
+			if err != nil {
+				return nil, fmt.Errorf("invalid default host URL: %w", err)
+			}
+			u.Path = "/"
+			t.Servers = []*openapi3.Server{{URL: u.String()}}
+		} else {
+			return nil, fmt.Errorf("no servers found in OpenAPI spec")
+		}
 	}
 	defaultServer, err := parseServer(t.Servers[0])
 	if err != nil {
@@ -39,6 +50,7 @@ func getOpenAPITools(t *openapi3.T) ([]types.Tool, error) {
 		}
 	}
 
+	// Generate a tool for each operation.
 	var (
 		toolNames    []string
 		tools        []types.Tool
@@ -54,6 +66,7 @@ func getOpenAPITools(t *openapi3.T) ([]types.Tool, error) {
 			}
 		}
 
+	operations:
 		for method, operation := range pathObj.Operations() {
 			// Handle operation-level server override, if one exists
 			operationServer := pathServer
@@ -103,10 +116,9 @@ func getOpenAPITools(t *openapi3.T) ([]types.Tool, error) {
 				},
 			}
 
-			toolNames = append(toolNames, tool.Parameters.Name)
-
-			// Handle query, path, and header parameters
-			for _, param := range operation.Parameters {
+			// Handle query, path, and header parameters, based on the parameters for this operation
+			// and the parameters for this path.
+			for _, param := range append(operation.Parameters, pathObj.Parameters...) {
 				arg := param.Value.Schema.Value
 
 				if arg.Description == "" {
@@ -161,7 +173,8 @@ func getOpenAPITools(t *openapi3.T) ([]types.Tool, error) {
 				}
 
 				if bodyMIME == "" {
-					return nil, fmt.Errorf("no supported MIME types found for request body in operation %s", operation.OperationID)
+					// No supported MIME types found, so just skip this operation and move on.
+					continue operations
 				}
 			}
 
@@ -226,6 +239,8 @@ func getOpenAPITools(t *openapi3.T) ([]types.Tool, error) {
 				return nil, err
 			}
 
+			// Register
+			toolNames = append(toolNames, tool.Parameters.Name)
 			tools = append(tools, tool)
 			operationNum++
 		}