feat(tools/looker): Validate project tool (#2430)

## Description

Validate changes to a LookML project and report LookML errors.

## PR Checklist

> Thank you for opening a Pull Request! Before submitting your PR, there
are a
> few things you can do to make sure it goes smoothly:

- [x] Make sure you reviewed

[CONTRIBUTING.md](https://github.com/googleapis/genai-toolbox/blob/main/CONTRIBUTING.md)
- [x] Make sure to open an issue as a

[bug/issue](https://github.com/googleapis/genai-toolbox/issues/new/choose)
  before writing your code! That way we can discuss the change, evaluate
  designs, and agree on the general idea
- [x] Ensure the tests and linter pass
- [x] Code coverage does not decrease (if any source code was changed)
- [x] Appropriate docs were updated (if necessary)
- [x] Make sure to add `!` if this involve a breaking change

.lycheeignore

@@ -37,8 +37,9 @@ https://dev.mysql.com/doc/refman/8.4/en/sql-prepared-statements.html
 https://dev.mysql.com/doc/refman/8.4/en/user-names.html
 
 # npmjs links can occasionally trigger rate limiting during high-frequency CI builds
-https://www.npmjs.com/package/@toolbox-sdk/core
 https://www.npmjs.com/package/@toolbox-sdk/adk
+https://www.npmjs.com/package/@toolbox-sdk/core
+https://www.npmjs.com/package/@toolbox-sdk/server
 https://www.oceanbase.com/
 
 # Ignore social media and blog profiles to reduce external request overhead

cmd/root.go

@@ -163,6 +163,7 @@ import (
 	_ "github.com/googleapis/genai-toolbox/internal/tools/looker/lookerrundashboard"
 	_ "github.com/googleapis/genai-toolbox/internal/tools/looker/lookerrunlook"
 	_ "github.com/googleapis/genai-toolbox/internal/tools/looker/lookerupdateprojectfile"
+	_ "github.com/googleapis/genai-toolbox/internal/tools/looker/lookervalidateproject"
 	_ "github.com/googleapis/genai-toolbox/internal/tools/mindsdb/mindsdbexecutesql"
 	_ "github.com/googleapis/genai-toolbox/internal/tools/mindsdb/mindsdbsql"
 	_ "github.com/googleapis/genai-toolbox/internal/tools/mongodb/mongodbaggregate"

cmd/root_test.go

@@ -2370,7 +2370,7 @@ func TestPrebuiltTools(t *testing.T) {
 			wantToolset: server.ToolsetConfigs{
 				"looker_tools": tools.ToolsetConfig{
 					Name:      "looker_tools",
-					ToolNames: []string{"get_models", "get_explores", "get_dimensions", "get_measures", "get_filters", "get_parameters", "query", "query_sql", "query_url", "get_looks", "run_look", "make_look", "get_dashboards", "run_dashboard", "make_dashboard", "add_dashboard_element", "add_dashboard_filter", "generate_embed_url", "health_pulse", "health_analyze", "health_vacuum", "dev_mode", "get_projects", "get_project_files", "get_project_file", "create_project_file", "update_project_file", "delete_project_file", "get_connections", "get_connection_schemas", "get_connection_databases", "get_connection_tables", "get_connection_table_columns"},
+					ToolNames: []string{"get_models", "get_explores", "get_dimensions", "get_measures", "get_filters", "get_parameters", "query", "query_sql", "query_url", "get_looks", "run_look", "make_look", "get_dashboards", "run_dashboard", "make_dashboard", "add_dashboard_element", "add_dashboard_filter", "generate_embed_url", "health_pulse", "health_analyze", "health_vacuum", "dev_mode", "get_projects", "get_project_files", "get_project_file", "create_project_file", "update_project_file", "delete_project_file", "validate_project", "get_connections", "get_connection_schemas", "get_connection_databases", "get_connection_tables", "get_connection_table_columns"},
 				},
 			},
 		},

docs/en/reference/prebuilt-tools.md

@@ -488,6 +488,7 @@ See [Usage Examples](../reference/cli.md#examples).
     *   `create_project_file`: Create a new LookML file.
     *   `update_project_file`: Update an existing LookML file.
     *   `delete_project_file`: Delete a LookML file.
+    *   `validate_project`: Check the syntax of a LookML project.
     *   `get_connections`: Get the available connections in a Looker instance.
     *   `get_connection_schemas`: Get the available schemas in a connection.
     *   `get_connection_databases`: Get the available databases in a connection.

docs/en/resources/tools/looker/looker-validate-project.md

@@ -0,0 +1,47 @@
+---
+title: "looker-validate-project"
+type: docs
+weight: 1
+description: >
+  A "looker-validate-project" tool checks the syntax of a LookML project and reports any errors
+aliases:
+- /resources/tools/looker-validate-project
+---
+
+## About
+
+A "looker-validate-project" tool checks the syntax of a LookML project and reports any errors
+
+It's compatible with the following sources:
+
+- [looker](../../sources/looker.md)
+
+`looker-validate-project` accepts a project_id parameter.
+
+## Example
+
+```yaml
+tools:
+    validate_project:
+        kind: looker-validate-project
+        source: looker-source
+        description: |
+          This tool checks a LookML project for syntax errors.
+
+          Prerequisite: The Looker session must be in Development Mode. Use `dev_mode: true` first.
+
+          Parameters:
+          - project_id (required): The unique ID of the LookML project.
+
+          Output:
+          A list of error details including the file path and line number, and also a list of models
+          that are not currently valid due to LookML errors.
+```
+
+## Reference
+
+| **field**   | **type** | **required** | **description**                                    |
+|-------------|:--------:|:------------:|----------------------------------------------------|
+| kind        |  string  |     true     | Must be "looker-validate-project".                 |
+| source      |  string  |     true     | Name of the source Looker instance.                |
+| description |  string  |     true     | Description of the tool that is passed to the LLM. |

internal/prebuiltconfigs/tools/looker.yaml

@@ -959,6 +959,21 @@ tools:
           Output:
           A confirmation message upon successful file deletion.
 
+    validate_project:
+        kind: looker-validate-project
+        source: looker-source
+        description: |
+          This tool checks a LookML project for syntax errors.
+
+          Prerequisite: The Looker session must be in Development Mode. Use `dev_mode: true` first.
+
+          Parameters:
+          - project_id (required): The unique ID of the LookML project.
+
+          Output:
+          A list of error details including the file path and line number, and also a list of models
+          that are not currently valid due to LookML errors.
+
     get_connections:
         kind: looker-get-connections
         source: looker-source
@@ -1072,6 +1087,7 @@ toolsets:
         - create_project_file
         - update_project_file
         - delete_project_file
+        - validate_project
         - get_connections
         - get_connection_schemas
         - get_connection_databases

internal/tools/looker/lookervalidateproject/lookervalidateproject.go

@@ -0,0 +1,177 @@
+// Copyright 2026 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//	http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+package lookervalidateproject
+
+import (
+	"context"
+	"fmt"
+
+	yaml "github.com/goccy/go-yaml"
+	"github.com/googleapis/genai-toolbox/internal/embeddingmodels"
+	"github.com/googleapis/genai-toolbox/internal/sources"
+	"github.com/googleapis/genai-toolbox/internal/tools"
+	"github.com/googleapis/genai-toolbox/internal/util"
+	"github.com/googleapis/genai-toolbox/internal/util/parameters"
+
+	"github.com/looker-open-source/sdk-codegen/go/rtl"
+	v4 "github.com/looker-open-source/sdk-codegen/go/sdk/v4"
+)
+
+const resourceType string = "looker-validate-project"
+
+func init() {
+	if !tools.Register(resourceType, newConfig) {
+		panic(fmt.Sprintf("tool type %q already registered", resourceType))
+	}
+}
+
+func newConfig(ctx context.Context, name string, decoder *yaml.Decoder) (tools.ToolConfig, error) {
+	actual := Config{Name: name}
+	if err := decoder.DecodeContext(ctx, &actual); err != nil {
+		return nil, err
+	}
+	return actual, nil
+}
+
+type compatibleSource interface {
+	UseClientAuthorization() bool
+	GetAuthTokenHeaderName() string
+	LookerApiSettings() *rtl.ApiSettings
+	GetLookerSDK(string) (*v4.LookerSDK, error)
+}
+
+type Config struct {
+	Name         string                 `yaml:"name" validate:"required"`
+	Type         string                 `yaml:"type" validate:"required"`
+	Source       string                 `yaml:"source" validate:"required"`
+	Description  string                 `yaml:"description" validate:"required"`
+	AuthRequired []string               `yaml:"authRequired"`
+	Annotations  *tools.ToolAnnotations `yaml:"annotations,omitempty"`
+}
+
+// validate interface
+var _ tools.ToolConfig = Config{}
+
+func (cfg Config) ToolConfigType() string {
+	return resourceType
+}
+
+func (cfg Config) Initialize(srcs map[string]sources.Source) (tools.Tool, error) {
+	projectIdParameter := parameters.NewStringParameter("project_id", "The id of the project to validate")
+	params := parameters.Parameters{projectIdParameter}
+
+	annotations := cfg.Annotations
+	if annotations == nil {
+		readOnlyHint := true
+		annotations = &tools.ToolAnnotations{
+			ReadOnlyHint: &readOnlyHint,
+		}
+	}
+
+	mcpManifest := tools.GetMcpManifest(cfg.Name, cfg.Description, cfg.AuthRequired, params, annotations)
+
+	// finish tool setup
+	return Tool{
+		Config:     cfg,
+		Parameters: params,
+		manifest: tools.Manifest{
+			Description:  cfg.Description,
+			Parameters:   params.Manifest(),
+			AuthRequired: cfg.AuthRequired,
+		},
+		mcpManifest: mcpManifest,
+	}, nil
+}
+
+// validate interface
+var _ tools.Tool = Tool{}
+
+type Tool struct {
+	Config
+	Parameters  parameters.Parameters `yaml:"parameters"`
+	manifest    tools.Manifest
+	mcpManifest tools.McpManifest
+}
+
+func (t Tool) ToConfig() tools.ToolConfig {
+	return t.Config
+}
+
+func (t Tool) Invoke(ctx context.Context, resourceMgr tools.SourceProvider, params parameters.ParamValues, accessToken tools.AccessToken) (any, error) {
+	source, err := tools.GetCompatibleSource[compatibleSource](resourceMgr, t.Source, t.Name, t.Type)
+	if err != nil {
+		return nil, err
+	}
+
+	logger, err := util.LoggerFromContext(ctx)
+	if err != nil {
+		return nil, fmt.Errorf("unable to get logger from ctx: %s", err)
+	}
+
+	sdk, err := source.GetLookerSDK(string(accessToken))
+	if err != nil {
+		return nil, fmt.Errorf("error getting sdk: %w", err)
+	}
+
+	mapParams := params.AsMap()
+	projectId, ok := mapParams["project_id"].(string)
+	if !ok {
+		return nil, fmt.Errorf("'project_id' must be a string, got %T", mapParams["project_id"])
+	}
+
+	resp, err := sdk.ValidateProject(projectId, "", source.LookerApiSettings())
+	if err != nil {
+		return nil, fmt.Errorf("error making validate_project request: %w", err)
+	}
+
+	logger.DebugContext(ctx, "Got response of %v\n", resp)
+
+	return resp, nil
+}
+
+func (t Tool) EmbedParams(ctx context.Context, paramValues parameters.ParamValues, embeddingModelsMap map[string]embeddingmodels.EmbeddingModel) (parameters.ParamValues, error) {
+	return parameters.EmbedParams(ctx, t.Parameters, paramValues, embeddingModelsMap, nil)
+}
+
+func (t Tool) Manifest() tools.Manifest {
+	return t.manifest
+}
+
+func (t Tool) McpManifest() tools.McpManifest {
+	return t.mcpManifest
+}
+
+func (t Tool) Authorized(verifiedAuthServices []string) bool {
+	return tools.IsAuthorized(t.AuthRequired, verifiedAuthServices)
+}
+
+func (t Tool) RequiresClientAuthorization(resourceMgr tools.SourceProvider) (bool, error) {
+	source, err := tools.GetCompatibleSource[compatibleSource](resourceMgr, t.Source, t.Name, t.Type)
+	if err != nil {
+		return false, err
+	}
+	return source.UseClientAuthorization(), nil
+}
+
+func (t Tool) GetAuthTokenHeaderName(resourceMgr tools.SourceProvider) (string, error) {
+	source, err := tools.GetCompatibleSource[compatibleSource](resourceMgr, t.Source, t.Name, t.Type)
+	if err != nil {
+		return "", err
+	}
+	return source.GetAuthTokenHeaderName(), nil
+}
+
+func (t Tool) GetParameters() parameters.Parameters {
+	return t.Parameters
+}

internal/tools/looker/lookervalidateproject/lookervalidateproject_test.go

@@ -0,0 +1,109 @@
+// Copyright 2026 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package lookervalidateproject_test
+
+import (
+	"strings"
+	"testing"
+
+	"github.com/google/go-cmp/cmp"
+	"github.com/googleapis/genai-toolbox/internal/server"
+	"github.com/googleapis/genai-toolbox/internal/testutils"
+	lkr "github.com/googleapis/genai-toolbox/internal/tools/looker/lookervalidateproject"
+)
+
+func TestParseFromYamlLookerValidateProject(t *testing.T) {
+	ctx, err := testutils.ContextWithNewLogger()
+	if err != nil {
+		t.Fatalf("unexpected error: %s", err)
+	}
+	tcs := []struct {
+		desc string
+		in   string
+		want server.ToolConfigs
+	}{
+		{
+			desc: "basic example",
+			in: `
+            kind: tools
+            name: example_tool
+            type: looker-validate-project
+            source: my-instance
+            description: some description
+				`,
+			want: server.ToolConfigs{
+				"example_tool": lkr.Config{
+					Name:         "example_tool",
+					Type:         "looker-validate-project",
+					Source:       "my-instance",
+					Description:  "some description",
+					AuthRequired: []string{},
+				},
+			},
+		},
+	}
+	for _, tc := range tcs {
+		t.Run(tc.desc, func(t *testing.T) {
+			// Parse contents
+			_, _, _, got, _, _, err := server.UnmarshalResourceConfig(ctx, testutils.FormatYaml(tc.in))
+			if err != nil {
+				t.Fatalf("unable to unmarshal: %s", err)
+			}
+			if diff := cmp.Diff(tc.want, got); diff != "" {
+				t.Fatalf("incorrect parse: diff %v", diff)
+			}
+		})
+	}
+
+}
+
+func TestFailParseFromYamlLookerValidateProject(t *testing.T) {
+	ctx, err := testutils.ContextWithNewLogger()
+	if err != nil {
+		t.Fatalf("unexpected error: %s", err)
+	}
+	tcs := []struct {
+		desc string
+		in   string
+		err  string
+	}{
+		{
+			desc: "Invalid method",
+			in: `
+            kind: tools
+            name: example_tool
+            type: looker-validate-project
+            source: my-instance
+            method: GOT
+            description: some description
+			`,
+			err: "error unmarshaling tools: unable to parse tool \"example_tool\" as type \"looker-validate-project\": [3:1] unknown field \"method\"\n   1 | authRequired: []\n   2 | description: some description\n>  3 | method: GOT\n       ^\n   4 | name: example_tool\n   5 | source: my-instance\n   6 | type: looker-validate-project",
+		},
+	}
+	for _, tc := range tcs {
+		t.Run(tc.desc, func(t *testing.T) {
+			// Parse contents
+			_, _, _, _, _, _, err := server.UnmarshalResourceConfig(ctx, testutils.FormatYaml(tc.in))
+			if err == nil {
+				t.Fatalf("expect parsing to fail")
+			}
+			errStr := err.Error()
+			if !strings.Contains(errStr, tc.err) {
+				t.Fatalf("unexpected error string: got %q, want substring %q", errStr, tc.err)
+			}
+		})
+	}
+
+}

tests/looker/looker_integration_test.go

@@ -222,6 +222,11 @@ func TestLooker(t *testing.T) {
 				"source":      "my-instance",
 				"description": "Simple tool to test end to end functionality.",
 			},
+			"validate_project": map[string]any{
+				"type":        "looker-validate-project",
+				"source":      "my-instance",
+				"description": "Simple tool to test end to end functionality.",
+			},
 			"generate_embed_url": map[string]any{
 				"type":        "looker-generate-embed-url",
 				"source":      "my-instance",
@@ -1446,6 +1451,23 @@ func TestLooker(t *testing.T) {
 			},
 		},
 	)
+	tests.RunToolGetTestByName(t, "validate_project",
+		map[string]any{
+			"validate_project": map[string]any{
+				"description":  "Simple tool to test end to end functionality.",
+				"authRequired": []any{},
+				"parameters": []any{
+					map[string]any{
+						"authSources": []any{},
+						"description": "The id of the project to validate",
+						"name":        "project_id",
+						"required":    true,
+						"type":        "string",
+					},
+				},
+			},
+		},
+	)
 	tests.RunToolGetTestByName(t, "generate_embed_url",
 		map[string]any{
 			"generate_embed_url": map[string]any{
@@ -1665,6 +1687,9 @@ func TestLooker(t *testing.T) {
 	wantResult = "deleted"
 	tests.RunToolInvokeParametersTest(t, "delete_project_file", []byte(`{"project_id": "the_look", "file_path": "foo.view.lkml"}`), wantResult)
 
+	wantResult = "\"errors\":[]"
+	tests.RunToolInvokeParametersTest(t, "validate_project", []byte(`{"project_id": "the_look"}`), wantResult)
+
 	wantResult = "production"
 	tests.RunToolInvokeParametersTest(t, "dev_mode", []byte(`{"devMode": false}`), wantResult)