feat(openapi): implement rest api tool (part 3) by AmaadMartin · Pull Request #386 · google/adk-js

AmaadMartin · 2026-05-27T20:31:35Z

Link to Issue or Description of Change

Problem:
Developers lacked a dynamic BaseTool class capable of mapping LLM function call arguments to REST API paths, headers, query params, and payloads.

Solution:
Implemented RestApiTool (Part 3 of 4):

rest_api_tool.ts: A robust tool implementation that leverages operation definitions to format HTTP requests, resolve credentials using ToolAuthHandler, execute API calls, and format responses.

Testing Plan

Unit Tests:

I have added or updated unit tests for my change.
All unit tests pass locally.

Summary of passed results:

Unit tested argument formatting, query param mapping, auth handling, and dynamic tool schema generation.
Actual Line Coverage by File:
- rest_api_tool.ts: 95.78%

Checklist

I have performed a self-review of my own code.
I have added tests that prove my fix is effective or that my feature works.
New and existing unit tests pass locally with my changes.

This implements RestApiTool for executing operations defined in OpenAPI specs. TAG=agy CONV=5d70d8ac-425c-4f8c-a969-97b17ecc66ce

…t 3) - Imported OperationEndpoint from openapi_spec_parser instead of redefining it. - Exported RestApiTool in common.ts. - Changed relative imports in rest_api_tool_test.ts to import from @google/adk. TAG=agy CONV=5d70d8ac-425c-4f8c-a969-97b17ecc66ce

kalenkevich · 2026-06-16T21:15:11Z

+    const method = this.endpoint.method.toUpperCase();
+    let url = `${this.endpoint.baseUrl}${this.endpoint.path}`;
+
+    const headers: Record<string, string> = {};
+
+    const queryParams = new URLSearchParams();
+    let body: unknown = undefined;
+
+    const parameters = this.operationParser.getParameters();
+    const paramsMap = new Map(parameters.map((p) => [p.name, p]));
+
+    const pathParams: Record<string, string> = {};
+    const bodyData: Record<string, unknown> = {};
+
+    for (const [argName, argValue] of Object.entries(args)) {
+      const param = paramsMap.get(argName);
+      if (!param) continue;
+
+      const originalName = param.originalName;
+      const location = param.paramLocation;
+
+      if (location === 'path') {
+        pathParams[originalName] = String(argValue);
+      } else if (location === 'query') {
+        queryParams.append(originalName, String(argValue));
+      } else if (location === 'header') {
+        headers[originalName] = String(argValue);
+      } else if (location === 'body') {
+        if (
+          originalName === 'body' ||
+          originalName === 'array' ||
+          originalName === ''
+        ) {
+          body = argValue;
+        } else {
+          bodyData[originalName] = argValue;
+        }
+      }
+    }
+
+    // Replace path parameters
+    for (const [key, value] of Object.entries(pathParams)) {
+      url = url.replace(`{${key}}`, value);
+    }
+
+    // Extract query parameters from path if any
+    const urlParts = url.split('?');
+    if (urlParts.length > 1) {
+      const pathQueryParams = new URLSearchParams(urlParts[1]);
+      for (const [key, value] of pathQueryParams.entries()) {
+        queryParams.append(key, value);
+      }
+      url = urlParts[0];
+    }
+
+    // Append query parameters
+    const queryString = queryParams.toString();
+    if (queryString) {
+      url += `?${queryString}`;
+    }


move this to separate util function

Done. Extracted this logic into a standalone helper function 'prepareRequestParams'.

kalenkevich · 2026-06-16T21:15:48Z

+    const requestBody = this.operation.requestBody;
+    const finalData =
+      body !== undefined
+        ? body
+        : Object.keys(bodyData).length > 0
+          ? bodyData
+          : undefined;
+
+    if (requestBody && 'content' in requestBody) {
+      const content = requestBody.content;
+      for (const [mimeType, _mediaTypeObject] of Object.entries(content)) {
+        if (finalData !== undefined) {
+          if (mimeType === 'application/json' || mimeType.endsWith('+json')) {
+            body =
+              typeof finalData === 'string'
+                ? finalData
+                : JSON.stringify(finalData);
+            headers['Content-Type'] = mimeType;
+          } else if (mimeType === 'application/x-www-form-urlencoded') {
+            body = new URLSearchParams(finalData as Record<string, string>);
+            // Fetch sets content-type automatically for URLSearchParams
+          } else if (mimeType === 'multipart/form-data') {
+            const formData = new FormData();
+            if (typeof finalData === 'object' && finalData !== null) {
+              for (const [key, value] of Object.entries(finalData)) {
+                formData.append(key, String(value));
+              }
+            }
+            body = formData;
+            // Fetch sets content-type with boundary automatically. DO NOT set it.
+          } else if (mimeType === 'text/plain') {
+            body = String(finalData);
+            headers['Content-Type'] = mimeType;
+          }
+        }
+        break; // Process only the first mime type
+      }
+    } else if (finalData !== undefined) {
+      // Fallback to JSON if no requestBody content specified but data exists
+      body =
+        typeof finalData === 'string' ? finalData : JSON.stringify(finalData);
+      headers['Content-Type'] = 'application/json';
+    }
+
+    // Handle Auth
+    url = applyCredential(url, headers, credential, this.authScheme);
+
+    // Apply dynamic headers from provider
+    if (this.headerProvider) {
+      const providerHeaders = this.headerProvider(context);
+      Object.assign(headers, providerHeaders);
+    }


same for body, move this body creating to separate function

Done. Extracted body formatting logic into a standalone helper function 'prepareRequestBody'.

kalenkevich · 2026-06-16T21:21:03Z

+  }
+
+  @experimental
+  public static fromParsedOperation(


avoid using static class methods, let it be just a util function that creates the RestApiTool

Done. Removed the static class method and replaced it with a standalone exported utility function 'createRestApiTool'.

…4) (google#387) * feat(openapi): implement openapi toolset and integration tests (part 4) This implements OpenAPIToolset and adds integration tests and fixtures. TAG=agy CONV=5d70d8ac-425c-4f8c-a969-97b17ecc66ce * refactor(openapi): resolve relative imports in OpenAPIToolset tests (part 4) - Exported OpenAPIToolset in common.ts. - Refactored relative imports inside openapi_toolset_test.ts and openapi_toolset_integration_test.ts to import from @google/adk. TAG=agy CONV=5d70d8ac-425c-4f8c-a969-97b17ecc66ce --------- Co-authored-by: Amaad Martin <amaadmartin@google.com>

…dy parsing helpers, replace static class method with standalone createRestApiTool utility

…unction

AmaadMartin changed the base branch from main to feat/openapi_tool_part2 May 27, 2026 20:38

Amaad Martin added 2 commits June 8, 2026 18:31

feat(openapi): implement rest api tool (part 3)

9805955

This implements RestApiTool for executing operations defined in OpenAPI specs. TAG=agy CONV=5d70d8ac-425c-4f8c-a969-97b17ecc66ce

AmaadMartin force-pushed the feat/openapi_tool_part3 branch 2 times, most recently from b45cb71 to e67c93f Compare June 9, 2026 01:34

AmaadMartin changed the base branch from feat/openapi_tool_part2 to main June 9, 2026 01:35

kalenkevich reviewed Jun 16, 2026

View reviewed changes

AmaadMartin and others added 3 commits June 18, 2026 12:54

refactor(openapi): address PR review comments, extract request and bo…

0c2d5ed

…dy parsing helpers, replace static class method with standalone createRestApiTool utility

fix(openapi): update OpenAPIToolset to use createRestApiTool helper f…

1f19d2e

…unction

AmaadMartin force-pushed the feat/openapi_tool_part3 branch from 1fa412e to 1f19d2e Compare June 18, 2026 20:00

kalenkevich approved these changes Jun 18, 2026

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feat(openapi): implement rest api tool (part 3)#386

feat(openapi): implement rest api tool (part 3)#386
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AmaadMartin:feat/openapi_tool_part3

AmaadMartin commented May 27, 2026

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kalenkevich Jun 16, 2026

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AmaadMartin Jun 17, 2026

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kalenkevich Jun 16, 2026

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AmaadMartin Jun 17, 2026

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kalenkevich Jun 16, 2026

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AmaadMartin commented May 27, 2026

Link to Issue or Description of Change

Testing Plan

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kalenkevich Jun 16, 2026

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