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feat(openapitoolset): add OpenAPI specification toolset - #451

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cpunion wants to merge 13 commits into
google:mainfrom
cpunion:feature/openapi-toolset
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feat(openapitoolset): add OpenAPI specification toolset#451
cpunion wants to merge 13 commits into
google:mainfrom
cpunion:feature/openapi-toolset

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@cpunion

@cpunion cpunion commented Dec 31, 2025

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Base on:
#455 feat(auth): add OAuth2/OIDC authentication package
#457 Feature/auth flow

  • Add openapitoolset package for generating tools from OpenAPI specs
  • Support JSON and YAML spec formats
  • Add RestApiTool with OAuth2, API key, and HTTP auth support
  • Add parser for operations, parameters, and request bodies
  • Add unit tests for parser, toolset, and rest_api_tool

- Add AuthConfig, AuthCredential, AuthScheme types
- Add AuthHandler for OAuth2 flow orchestration
- Add CredentialManager and CredentialService for token management
- Add OAuth2 token exchange helpers
- Add unit tests for auth package
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Summary of Changes

Hello @cpunion, I'm Gemini Code Assist1! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request significantly enhances the system's ability to interact with external APIs by introducing a dedicated toolset for OpenAPI specifications. It allows developers to define API interactions using standard OpenAPI documents, which are then automatically converted into executable tools. This streamlines the process of integrating new services and ensures consistent API consumption patterns, complete with flexible authentication mechanisms.

Highlights

  • New OpenAPI Toolset Package: Introduces a new openapitoolset package for generating tools directly from OpenAPI specifications.
  • OpenAPI Specification Parsing: Adds robust parsing capabilities for OpenAPI specifications, supporting both JSON and YAML formats to extract API operations, parameters, request bodies, and responses.
  • RestApiTool Implementation: Includes a RestApiTool that can execute REST API calls based on parsed OpenAPI operations, handling URL construction, request bodies, and response processing.
  • Authentication Support: The RestApiTool supports various authentication schemes including OAuth2, API Key, and HTTP Basic/Bearer authentication, with a shared credential service for persistent token storage.
  • Comprehensive Unit Tests: New unit tests have been added for the parser, the RestApiTool, and the overall toolset creation and configuration, ensuring reliability and correctness.

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Code Review

This pull request introduces a new toolset for generating tools from OpenAPI specifications. The implementation covers parsing the spec, creating RestApiTool instances, and handling various authentication schemes. The code is well-structured and includes a good set of unit tests. I've identified a few areas for improvement, including a correctness issue in parameter parsing, a missing feature in authentication handling, and a misleading function signature. Overall, this is a great addition.

Comment on lines +172 to +182
var params []Parameter

// Parse path-level parameters
if pathParams, ok := pathItem["parameters"].([]any); ok {
params = append(params, parseParameterList(pathParams)...)
}

// Parse operation-level parameters (override path-level)
if opParams, ok := op["parameters"].([]any); ok {
params = append(params, parseParameterList(opParams)...)
}

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high

The current implementation appends both path-level and operation-level parameters. According to the OpenAPI specification, parameters defined at the operation level should override any parameters with the same name and location (in) defined at the path level. Simply appending them can lead to duplicate parameters and incorrect API requests.

To fix this, you can use a map to collect parameters, which will naturally handle the overriding, and then convert the map back to a slice.

paramMap := make(map[string]Parameter)

	// Parse path-level parameters
	if pathParams, ok := pathItem["parameters"].([]any); ok {
		for _, p := range parseParameterList(pathParams) {
			paramMap[p.Name+":"+p.In] = p
		}
	}

	// Parse operation-level parameters (overrides path-level)
	if opParams, ok := op["parameters"].([]any); ok {
		for _, p := range parseParameterList(opParams) {
			paramMap[p.Name+":"+p.In] = p
		}
	}

	params := make([]Parameter, 0, len(paramMap))
	for _, p := range paramMap {
		params = append(params, p)
	}

Comment on lines +107 to +110
parsed, err := parseOperation(path, method, op, baseURL, pathItemMap)
if err != nil {
continue // Skip invalid operations
}

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medium

The parseOperation function is declared to return an error, but it never actually returns one. This makes the error handling here redundant and the function's signature misleading. Since the parsing logic is very lenient and designed to skip invalid parts rather than fail, it would be clearer to remove the error return type from parseOperation altogether.

This would also require changing the signature of parseOperation on line 121 and its return statement on line 156.

Suggested change
parsed, err := parseOperation(path, method, op, baseURL, pathItemMap)
if err != nil {
continue // Skip invalid operations
}
parsed := parseOperation(path, method, op, baseURL, pathItemMap)

Comment on lines +316 to +325
case auth.AuthCredentialTypeAPIKey:
if t.authCredential.APIKey != "" && t.authScheme != nil {
if apiKeyScheme, ok := t.authScheme.(*auth.APIKeyScheme); ok {
switch apiKeyScheme.In {
case auth.APIKeyInHeader:
headers[apiKeyScheme.Name] = t.authCredential.APIKey
}
}
}
}

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medium

The current implementation for API key authentication only supports placing the key in the request header. The OpenAPI specification also allows API keys to be passed in query parameters (in: query). This functionality is missing.

To add support for this, you would need to:

  1. Update buildURL to check if the auth scheme is an API key in a query parameter, and if so, add it to the query values.
  2. Ensure this function, getAuthHeaders, only handles the in: header case for API keys.

@cpunion cpunion mentioned this pull request Dec 31, 2025
@cpunion
cpunion force-pushed the feature/openapi-toolset branch from 9f2e0c9 to 22ebdb7 Compare January 1, 2026 04:01
Add support for tools to request authentication credentials during execution:

- Add RequestedAuthConfigs field to EventActions for storing auth requests
- Implement GenerateAuthEvent to convert auth requests to adk_request_credential function calls
- Add RequestAuthConfig method to ToolContext for tools to request authentication
- Add AuthConfig field to Tool interface for tools to declare auth requirements
- Integrate auth event generation into the LLM base flow

Also fix test comparisons to ignore RequestedAuthConfigs field initialization
and add UTC timezone setup in database tests for consistent timestamp formatting.
@cpunion
cpunion force-pushed the feature/openapi-toolset branch from 22ebdb7 to 4a3116a Compare January 1, 2026 13:37
@cpunion
cpunion force-pushed the feature/openapi-toolset branch from 4a3116a to d6d4100 Compare January 1, 2026 14:59
Add a new toolset that automatically generates tools from OpenAPI/Swagger
specifications, enabling agents to interact with REST APIs.

Key components:
- OpenAPI spec parser supporting v3.0/v3.1 with JSON Schema conversion
- RestApiTool for executing HTTP requests with path/query/body parameters
- Toolset for loading specs from file/URL and generating tools
- OAuth2 authentication support with credential request flow
- Example demonstrating GitHub API integration with device auth flow
@cpunion
cpunion force-pushed the feature/openapi-toolset branch from d6d4100 to 3d1bdc7 Compare January 1, 2026 15:02
@cpunion

cpunion commented Jan 1, 2026

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/gemini review

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Code Review

This pull request introduces a significant and well-structured feature: an OpenAPI toolset with comprehensive authentication support, including OAuth2. The new auth package is robust, with a clear separation of concerns for schemes, credentials, and lifecycle management. The use of registries for exchangers and refreshers is a good design choice for extensibility. The OpenAPI parser and the RestApiTool provide a powerful way to generate tools from specifications. I've identified a critical issue in the example's custom OAuth2 code exchange logic that should be refactored to use the standard library for better security and simplicity. Additionally, there are a couple of medium-severity issues related to parsing and key generation that could be improved for robustness and clarity. Overall, this is an excellent addition to the ADK.

Comment thread examples/openapi/oauth2handler/handler.go
Comment thread auth/auth_config.go
Comment thread examples/openapi/main.go Outdated
@jjsasha63

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Thank you for this, and I am sorry it took us eight months to reply. That delay is on us.

An OpenAPI toolset is genuinely missing from adk-go and we do want one. This PR cannot be the vehicle, for three reasons.

The auth half conflicts with a decision we have since made. This PR is stacked on #455 and #457. We closed #455 because adk-go had by then landed its own auth package, built on golang.org/x/oauth2 rather than on a ported AuthConfig/CredentialManager layer; you closed #457 yourself. Either way, the foundation this PR sits on is not one we can take now. Main also has auth.Transport, an http.RoundTripper that resolves a credential per request, which removes the need for the getAuthHeaders layer in rest_api_tool.go entirely.

The parser does not resolve $ref. parser.go:98 skips $ref at the path-item level, and parameter and request-body schemas are copied through as raw maps with no components/schemas resolution anywhere in the file. A parameter whose schema is a $ref reaches convertSchemaToGenai with no type, so it falls back to string at rest_api_tool.go:92. Most real-world specs would therefore produce tools with wrong signatures rather than an error, which is the hardest kind of failure to notice. Separately, parseParameters still appends the path-level and operation-level lists instead of overriding by name and location, which the automated review flagged as high severity in December and which is still open.

The branch has moved out from under itself. Main is 322 commits ahead, with 16 conflicting files including go.mod and go.sum, and the module path is now google.golang.org/adk/v2, so the google.golang.org/adk/auth imports no longer resolve. Reconciling that is a rewrite rather than a rebase.

So we are closing this one. We would very much welcome a smaller PR covering only tool/openapitoolset, built on an established OpenAPI library and taking credentials through the existing auth.CredentialProvider seam. Which library to depend on is a decision we should make before anyone writes the code, so I am opening a tracking issue for it now and will link it here. Please comment there if you would like to pick this up.

@jjsasha63

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Tracking issue for the scoped version, as promised above: #1464. It records the constraints (credentials through auth.CredentialProvider, separate Go module, $ref resolution required) and asks for a decision on which OpenAPI library to depend on.

@cpunion, you have first refusal on it if you want it.

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