feat(server): add Tool call error categories by duwenxin99 · Pull Request #2387 · googleapis/mcp-toolbox

duwenxin99 · 2026-01-29T17:05:01Z

Create Agent vs Server error types to distinguish between the two types.

gemini-code-assist · 2026-01-29T17:05:16Z

Summary of Changes

Hello @duwenxin99, 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 introduces a structured error handling mechanism by defining distinct error categories for agent and server-side issues. This foundational change aims to improve the clarity and diagnosability of errors within the system, making it easier to identify the source of a problem and streamline debugging efforts.

Highlights

New Error Definitions File: A new file, internal/util/errors.go, has been added to centralize and define custom error types for the server.
Error Categorization: Introduced an ErrorCategory enum with CategoryAgent and CategoryServer to explicitly classify the origin of errors.
Custom Error Interface: Defined a ToolboxError interface that all custom errors must satisfy, ensuring a consistent error structure.
Structured Error Types: Implemented AgentError and ServerError structs, both of which fulfill the error interface and provide a Category() method for type-specific error reporting. ServerError also includes a Cause field for wrapping underlying errors.

Using Gemini Code Assist

The full guide for Gemini Code Assist can be found on our documentation page, here are some quick tips.

Invoking Gemini

You can request assistance from Gemini at any point by creating a comment using either /gemini <command> or @gemini-code-assist <command>. Below is a summary of the supported commands on the current page.

Feature	Command	Description
Code Review	`/gemini review`	Performs a code review for the current pull request in its current state.
Pull Request Summary	`/gemini summary`	Provides a summary of the current pull request in its current state.
Comment	@gemini-code-assist	Responds in comments when explicitly tagged, both in pull request comments and review comments.
Help	`/gemini help`	Displays a list of available commands.

Customization

To customize Gemini Code Assist for GitHub experience, repository maintainers can create a configuration file and/or provide a custom code review style guide (such as PEP-8 for Python) by creating and adding files to a .gemini/ folder in the base of the repository. Detailed instructions can be found here.

Limitations & Feedback

Gemini Code Assist may make mistakes. Please leave feedback on any instances where its feedback is incorrect or counter productive. You can react with 👍 and 👎 on @gemini-code-assist comments. If you're interested in giving your feedback about your experience with Gemini Code Assist for Github and other Google products, sign up here.

You can also get AI-powered code generation, chat, as well as code reviews directly in the IDE at no cost with the Gemini Code Assist IDE Extension.

Review the Privacy Notices, Generative AI Prohibited Use Policy, Terms of Service, and learn how to configure Gemini Code Assist in GitHub here. Gemini can make mistakes, so double check it and use code with caution. ↩

gemini-code-assist

Code Review

This pull request introduces new error types, AgentError and ServerError, to categorize errors originating from the agent or the server. The changes are well-contained in a new errors.go file. My feedback includes suggestions to improve the new error abstractions by making the ToolboxError interface more specific and by adding support for Go's standard error wrapping to ServerError.

🤖 I have created a release *beep* *boop* --- ## [0.27.0](v0.26.0...v0.27.0) (2026-02-12) ### ⚠ BREAKING CHANGES * Update configuration file v2 ([#2369](https://github.com/googleapis/genai-toolbox/issues/2369))([293c1d6](https://github.com/googleapis/genai-toolbox/commit/293c1d6889c39807855ba5e01d4c13ba2a4c50ce)) * Update/add detailed telemetry for mcp endpoint compliant with OTEL semantic convention ([#1987](#1987)) ([478a0bd](478a0bd)) ### Features * **cli/invoke:** Add support for direct tool invocation from CLI ([#2353](#2353)) ([6e49ba4](6e49ba4)) * **cli/skills:** Add support for generating agent skills from toolset ([#2392](#2392)) ([80ef346](80ef346)) * **cloud-logging-admin:** Add source, tools, integration test and docs ([#2137](#2137)) ([252fc30](252fc30)) * **cockroachdb:** Add CockroachDB integration with cockroach-go ([#2006](#2006)) ([1fdd99a](1fdd99a)) * **prebuiltconfigs/alloydb-omni:** Implement Alloydb omni dataplane tools ([#2340](#2340)) ([e995349](e995349)) * **server:** Add Tool call error categories ([#2387](#2387)) ([32cb4db](32cb4db)) * **tools/looker:** support `looker-validate-project` tool ([#2430](#2430)) ([a15a128](a15a128)) ### Bug Fixes * **dataplex:** Capture GCP HTTP errors in MCP Toolbox ([#2347](#2347)) ([1d7c498](1d7c498)) * **sources/cockroachdb:** Update kind to type ([#2465](#2465)) ([2d341ac](2d341ac)) * Surface Dataplex API errors in MCP results ([#2347](https://github.com/googleapis/genai-toolbox/pull/2347))([1d7c498](https://github.com/googleapis/genai-toolbox/commit/1d7c4981164c34b4d7bc8edecfd449f57ad11e15)) --- This PR was generated with [Release Please](https://github.com/googleapis/release-please). See [documentation](https://github.com/googleapis/release-please#release-please). --------- Co-authored-by: release-please[bot] <55107282+release-please[bot]@users.noreply.github.com> Co-authored-by: Yuan Teoh <45984206+Yuan325@users.noreply.github.com>

🤖 I have created a release *beep* *boop* --- ## [0.27.0](v0.26.0...v0.27.0) (2026-02-12) ### ⚠ BREAKING CHANGES * Update configuration file v2 ([#2369](https://github.com/googleapis/genai-toolbox/issues/2369))([293c1d6](https://github.com/googleapis/genai-toolbox/commit/293c1d6889c39807855ba5e01d4c13ba2a4c50ce)) * Update/add detailed telemetry for mcp endpoint compliant with OTEL semantic convention ([#1987](#1987)) ([478a0bd](478a0bd)) ### Features * **cli/invoke:** Add support for direct tool invocation from CLI ([#2353](#2353)) ([6e49ba4](6e49ba4)) * **cli/skills:** Add support for generating agent skills from toolset ([#2392](#2392)) ([80ef346](80ef346)) * **cloud-logging-admin:** Add source, tools, integration test and docs ([#2137](#2137)) ([252fc30](252fc30)) * **cockroachdb:** Add CockroachDB integration with cockroach-go ([#2006](#2006)) ([1fdd99a](1fdd99a)) * **prebuiltconfigs/alloydb-omni:** Implement Alloydb omni dataplane tools ([#2340](#2340)) ([e995349](e995349)) * **server:** Add Tool call error categories ([#2387](#2387)) ([32cb4db](32cb4db)) * **tools/looker:** support `looker-validate-project` tool ([#2430](#2430)) ([a15a128](a15a128)) ### Bug Fixes * **dataplex:** Capture GCP HTTP errors in MCP Toolbox ([#2347](#2347)) ([1d7c498](1d7c498)) * **sources/cockroachdb:** Update kind to type ([#2465](#2465)) ([2d341ac](2d341ac)) * Surface Dataplex API errors in MCP results ([#2347](https://github.com/googleapis/genai-toolbox/pull/2347))([1d7c498](https://github.com/googleapis/genai-toolbox/commit/1d7c4981164c34b4d7bc8edecfd449f57ad11e15)) --- This PR was generated with [Release Please](https://github.com/googleapis/release-please). See [documentation](https://github.com/googleapis/release-please#release-please). --------- Co-authored-by: release-please[bot] <55107282+release-please[bot]@users.noreply.github.com> Co-authored-by: Yuan Teoh <45984206+Yuan325@users.noreply.github.com> c5524d3

🤖 I have created a release *beep* *boop* --- ## [0.27.0](googleapis/mcp-toolbox@v0.26.0...v0.27.0) (2026-02-12) ### ⚠ BREAKING CHANGES * Update configuration file v2 ([googleapis#2369](https://github.com/googleapis/genai-toolbox/issues/2369))([293c1d6](https://github.com/googleapis/genai-toolbox/commit/293c1d6889c39807855ba5e01d4c13ba2a4c50ce)) * Update/add detailed telemetry for mcp endpoint compliant with OTEL semantic convention ([googleapis#1987](googleapis#1987)) ([478a0bd](googleapis@478a0bd)) ### Features * **cli/invoke:** Add support for direct tool invocation from CLI ([googleapis#2353](googleapis#2353)) ([6e49ba4](googleapis@6e49ba4)) * **cli/skills:** Add support for generating agent skills from toolset ([googleapis#2392](googleapis#2392)) ([80ef346](googleapis@80ef346)) * **cloud-logging-admin:** Add source, tools, integration test and docs ([googleapis#2137](googleapis#2137)) ([252fc30](googleapis@252fc30)) * **cockroachdb:** Add CockroachDB integration with cockroach-go ([googleapis#2006](googleapis#2006)) ([1fdd99a](googleapis@1fdd99a)) * **prebuiltconfigs/alloydb-omni:** Implement Alloydb omni dataplane tools ([googleapis#2340](googleapis#2340)) ([e995349](googleapis@e995349)) * **server:** Add Tool call error categories ([googleapis#2387](googleapis#2387)) ([32cb4db](googleapis@32cb4db)) * **tools/looker:** support `looker-validate-project` tool ([googleapis#2430](googleapis#2430)) ([a15a128](googleapis@a15a128)) ### Bug Fixes * **dataplex:** Capture GCP HTTP errors in MCP Toolbox ([googleapis#2347](googleapis#2347)) ([1d7c498](googleapis@1d7c498)) * **sources/cockroachdb:** Update kind to type ([googleapis#2465](googleapis#2465)) ([2d341ac](googleapis@2d341ac)) * Surface Dataplex API errors in MCP results ([googleapis#2347](https://github.com/googleapis/genai-toolbox/pull/2347))([1d7c498](https://github.com/googleapis/genai-toolbox/commit/1d7c4981164c34b4d7bc8edecfd449f57ad11e15)) --- This PR was generated with [Release Please](https://github.com/googleapis/release-please). See [documentation](https://github.com/googleapis/release-please#release-please). --------- Co-authored-by: release-please[bot] <55107282+release-please[bot]@users.noreply.github.com> Co-authored-by: Yuan Teoh <45984206+Yuan325@users.noreply.github.com> c5524d3

Create Agent vs Server error types to distinguish between the two types. --------- Co-authored-by: Averi Kitsch <akitsch@google.com>

🤖 I have created a release *beep* *boop* --- ## [0.27.0](v0.26.0...v0.27.0) (2026-02-12) ### ⚠ BREAKING CHANGES * Update configuration file v2 ([#2369](https://github.com/googleapis/genai-toolbox/issues/2369))([293c1d6](https://github.com/googleapis/genai-toolbox/commit/293c1d6889c39807855ba5e01d4c13ba2a4c50ce)) * Update/add detailed telemetry for mcp endpoint compliant with OTEL semantic convention ([#1987](#1987)) ([478a0bd](478a0bd)) ### Features * **cli/invoke:** Add support for direct tool invocation from CLI ([#2353](#2353)) ([6e49ba4](6e49ba4)) * **cli/skills:** Add support for generating agent skills from toolset ([#2392](#2392)) ([80ef346](80ef346)) * **cloud-logging-admin:** Add source, tools, integration test and docs ([#2137](#2137)) ([252fc30](252fc30)) * **cockroachdb:** Add CockroachDB integration with cockroach-go ([#2006](#2006)) ([1fdd99a](1fdd99a)) * **prebuiltconfigs/alloydb-omni:** Implement Alloydb omni dataplane tools ([#2340](#2340)) ([e995349](e995349)) * **server:** Add Tool call error categories ([#2387](#2387)) ([32cb4db](32cb4db)) * **tools/looker:** support `looker-validate-project` tool ([#2430](#2430)) ([a15a128](a15a128)) ### Bug Fixes * **dataplex:** Capture GCP HTTP errors in MCP Toolbox ([#2347](#2347)) ([1d7c498](1d7c498)) * **sources/cockroachdb:** Update kind to type ([#2465](#2465)) ([2d341ac](2d341ac)) * Surface Dataplex API errors in MCP results ([#2347](https://github.com/googleapis/genai-toolbox/pull/2347))([1d7c498](https://github.com/googleapis/genai-toolbox/commit/1d7c4981164c34b4d7bc8edecfd449f57ad11e15)) --- This PR was generated with [Release Please](https://github.com/googleapis/release-please). See [documentation](https://github.com/googleapis/release-please#release-please). --------- Co-authored-by: release-please[bot] <55107282+release-please[bot]@users.noreply.github.com> Co-authored-by: Yuan Teoh <45984206+Yuan325@users.noreply.github.com>

Create Agent vs Server error types to distinguish between the two types. --------- Co-authored-by: Averi Kitsch <akitsch@google.com>

🤖 I have created a release *beep* *boop* --- ## [0.27.0](googleapis/mcp-toolbox@v0.26.0...v0.27.0) (2026-02-12) ### ⚠ BREAKING CHANGES * Update configuration file v2 ([googleapis#2369](https://github.com/googleapis/genai-toolbox/issues/2369))([293c1d6](https://github.com/googleapis/genai-toolbox/commit/293c1d6889c39807855ba5e01d4c13ba2a4c50ce)) * Update/add detailed telemetry for mcp endpoint compliant with OTEL semantic convention ([googleapis#1987](googleapis#1987)) ([478a0bd](googleapis@478a0bd)) ### Features * **cli/invoke:** Add support for direct tool invocation from CLI ([googleapis#2353](googleapis#2353)) ([6e49ba4](googleapis@6e49ba4)) * **cli/skills:** Add support for generating agent skills from toolset ([googleapis#2392](googleapis#2392)) ([80ef346](googleapis@80ef346)) * **cloud-logging-admin:** Add source, tools, integration test and docs ([googleapis#2137](googleapis#2137)) ([252fc30](googleapis@252fc30)) * **cockroachdb:** Add CockroachDB integration with cockroach-go ([googleapis#2006](googleapis#2006)) ([1fdd99a](googleapis@1fdd99a)) * **prebuiltconfigs/alloydb-omni:** Implement Alloydb omni dataplane tools ([googleapis#2340](googleapis#2340)) ([e995349](googleapis@e995349)) * **server:** Add Tool call error categories ([googleapis#2387](googleapis#2387)) ([32cb4db](googleapis@32cb4db)) * **tools/looker:** support `looker-validate-project` tool ([googleapis#2430](googleapis#2430)) ([a15a128](googleapis@a15a128)) ### Bug Fixes * **dataplex:** Capture GCP HTTP errors in MCP Toolbox ([googleapis#2347](googleapis#2347)) ([1d7c498](googleapis@1d7c498)) * **sources/cockroachdb:** Update kind to type ([googleapis#2465](googleapis#2465)) ([2d341ac](googleapis@2d341ac)) * Surface Dataplex API errors in MCP results ([googleapis#2347](https://github.com/googleapis/genai-toolbox/pull/2347))([1d7c498](https://github.com/googleapis/genai-toolbox/commit/1d7c4981164c34b4d7bc8edecfd449f57ad11e15)) --- This PR was generated with [Release Please](https://github.com/googleapis/release-please). See [documentation](https://github.com/googleapis/release-please#release-please). --------- Co-authored-by: release-please[bot] <55107282+release-please[bot]@users.noreply.github.com> Co-authored-by: Yuan Teoh <45984206+Yuan325@users.noreply.github.com>

Create Agent vs Server error types to distinguish between the two types. --------- Co-authored-by: Averi Kitsch <akitsch@google.com>

🤖 I have created a release *beep* *boop* --- ## [0.27.0](googleapis/mcp-toolbox@v0.26.0...v0.27.0) (2026-02-12) ### ⚠ BREAKING CHANGES * Update configuration file v2 ([googleapis#2369](https://github.com/googleapis/genai-toolbox/issues/2369))([293c1d6](https://github.com/googleapis/genai-toolbox/commit/293c1d6889c39807855ba5e01d4c13ba2a4c50ce)) * Update/add detailed telemetry for mcp endpoint compliant with OTEL semantic convention ([googleapis#1987](googleapis#1987)) ([478a0bd](googleapis@478a0bd)) ### Features * **cli/invoke:** Add support for direct tool invocation from CLI ([googleapis#2353](googleapis#2353)) ([6e49ba4](googleapis@6e49ba4)) * **cli/skills:** Add support for generating agent skills from toolset ([googleapis#2392](googleapis#2392)) ([80ef346](googleapis@80ef346)) * **cloud-logging-admin:** Add source, tools, integration test and docs ([googleapis#2137](googleapis#2137)) ([252fc30](googleapis@252fc30)) * **cockroachdb:** Add CockroachDB integration with cockroach-go ([googleapis#2006](googleapis#2006)) ([1fdd99a](googleapis@1fdd99a)) * **prebuiltconfigs/alloydb-omni:** Implement Alloydb omni dataplane tools ([googleapis#2340](googleapis#2340)) ([e995349](googleapis@e995349)) * **server:** Add Tool call error categories ([googleapis#2387](googleapis#2387)) ([32cb4db](googleapis@32cb4db)) * **tools/looker:** support `looker-validate-project` tool ([googleapis#2430](googleapis#2430)) ([a15a128](googleapis@a15a128)) ### Bug Fixes * **dataplex:** Capture GCP HTTP errors in MCP Toolbox ([googleapis#2347](googleapis#2347)) ([1d7c498](googleapis@1d7c498)) * **sources/cockroachdb:** Update kind to type ([googleapis#2465](googleapis#2465)) ([2d341ac](googleapis@2d341ac)) * Surface Dataplex API errors in MCP results ([googleapis#2347](https://github.com/googleapis/genai-toolbox/pull/2347))([1d7c498](https://github.com/googleapis/genai-toolbox/commit/1d7c4981164c34b4d7bc8edecfd449f57ad11e15)) --- This PR was generated with [Release Please](https://github.com/googleapis/release-please). See [documentation](https://github.com/googleapis/release-please#release-please). --------- Co-authored-by: release-please[bot] <55107282+release-please[bot]@users.noreply.github.com> Co-authored-by: Yuan Teoh <45984206+Yuan325@users.noreply.github.com>

🤖 I have created a release *beep* *boop* --- ## [0.27.0](googleapis/mcp-toolbox@v0.26.0...v0.27.0) (2026-02-12) ### ⚠ BREAKING CHANGES * Update configuration file v2 ([#2369](https://github.com/googleapis/genai-toolbox/issues/2369))([293c1d6](https://github.com/googleapis/genai-toolbox/commit/293c1d6889c39807855ba5e01d4c13ba2a4c50ce)) * Update/add detailed telemetry for mcp endpoint compliant with OTEL semantic convention ([#1987](googleapis/mcp-toolbox#1987)) ([478a0bd](googleapis/mcp-toolbox@478a0bd)) ### Features * **cli/invoke:** Add support for direct tool invocation from CLI ([#2353](googleapis/mcp-toolbox#2353)) ([6e49ba4](googleapis/mcp-toolbox@6e49ba4)) * **cli/skills:** Add support for generating agent skills from toolset ([#2392](googleapis/mcp-toolbox#2392)) ([80ef346](googleapis/mcp-toolbox@80ef346)) * **cloud-logging-admin:** Add source, tools, integration test and docs ([#2137](googleapis/mcp-toolbox#2137)) ([252fc30](googleapis/mcp-toolbox@252fc30)) * **cockroachdb:** Add CockroachDB integration with cockroach-go ([#2006](googleapis/mcp-toolbox#2006)) ([1fdd99a](googleapis/mcp-toolbox@1fdd99a)) * **prebuiltconfigs/alloydb-omni:** Implement Alloydb omni dataplane tools ([#2340](googleapis/mcp-toolbox#2340)) ([e995349](googleapis/mcp-toolbox@e995349)) * **server:** Add Tool call error categories ([#2387](googleapis/mcp-toolbox#2387)) ([32cb4db](googleapis/mcp-toolbox@32cb4db)) * **tools/looker:** support `looker-validate-project` tool ([#2430](googleapis/mcp-toolbox#2430)) ([a15a128](googleapis/mcp-toolbox@a15a128)) ### Bug Fixes * **dataplex:** Capture GCP HTTP errors in MCP Toolbox ([#2347](googleapis/mcp-toolbox#2347)) ([1d7c498](googleapis/mcp-toolbox@1d7c498)) * **sources/cockroachdb:** Update kind to type ([#2465](googleapis/mcp-toolbox#2465)) ([2d341ac](googleapis/mcp-toolbox@2d341ac)) * Surface Dataplex API errors in MCP results ([#2347](https://github.com/googleapis/genai-toolbox/pull/2347))([1d7c498](https://github.com/googleapis/genai-toolbox/commit/1d7c4981164c34b4d7bc8edecfd449f57ad11e15)) --- This PR was generated with [Release Please](https://github.com/googleapis/release-please). See [documentation](https://github.com/googleapis/release-please#release-please). --------- Co-authored-by: release-please[bot] <55107282+release-please[bot]@users.noreply.github.com> Co-authored-by: Yuan Teoh <45984206+Yuan325@users.noreply.github.com>

feat(server): add Tool call error categories

32b2c93

duwenxin99 requested a review from a team January 29, 2026 17:05

blunderbuss-gcf Bot assigned Yuan325 Jan 29, 2026

gemini-code-assist Bot reviewed Jan 29, 2026

View reviewed changes

Comment thread internal/util/errors.go

Comment thread internal/util/errors.go Outdated

add constructors

bb58baf

duwenxin99 assigned averikitsch and unassigned Yuan325 Jan 29, 2026

duwenxin99 and others added 6 commits January 29, 2026 18:00

Merge branch 'main' into err

b6fa798

add error code

4624445

add client err

62d96a6

update comment

54f9a3d

Merge branch 'main' into err

ac544d0

update agentError constructor

0c5285c

averikitsch assigned Yuan325 Feb 3, 2026

Yuan325 requested changes Feb 3, 2026

View reviewed changes

Comment thread internal/util/errors.go

Comment thread internal/util/errors.go

Comment thread internal/util/errors.go

reset package location

da2c103

duwenxin99 force-pushed the err branch from b6835ae to da2c103 Compare February 4, 2026 18:50

Merge branch 'main' into err

fc5d3ef

Yuan325 approved these changes Feb 4, 2026

View reviewed changes

Comment thread internal/util/errors.go Outdated

duwenxin99 and others added 4 commits February 4, 2026 14:40

nit

1f9cd1b

add error formatting

e73768c

Merge branch 'main' into err

637f3b9

Merge branch 'main' into err

9a05e7e

duwenxin99 enabled auto-merge (squash) February 12, 2026 13:12

duwenxin99 merged commit 32cb4db into main Feb 12, 2026
13 checks passed

duwenxin99 deleted the err branch February 12, 2026 13:34

release-please Bot mentioned this pull request Feb 11, 2026

chore(main): release 0.27.0 #2363

Merged

BrewTestBot mentioned this pull request Feb 13, 2026

mcp-toolbox 0.27.0 Homebrew/homebrew-core#267330

Merged

rahulpinto19 pushed a commit that referenced this pull request Feb 16, 2026

feat(server): add Tool call error categories (#2387)

9ed0e76

Create Agent vs Server error types to distinguish between the two types. --------- Co-authored-by: Averi Kitsch <akitsch@google.com>

github-actions Bot mentioned this pull request Mar 12, 2026

chore(main): release 0.29.0 #2608

Merged

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

feat(server): add Tool call error categories#2387

feat(server): add Tool call error categories#2387
duwenxin99 merged 14 commits intomainfrom
err

duwenxin99 commented Jan 29, 2026

Uh oh!

gemini-code-assist Bot commented Jan 29, 2026

Uh oh!

gemini-code-assist Bot left a comment

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

3 participants

Conversation

duwenxin99 commented Jan 29, 2026

Uh oh!

gemini-code-assist Bot commented Jan 29, 2026

Summary of Changes

Highlights

Footnotes

Uh oh!

gemini-code-assist Bot left a comment

Choose a reason for hiding this comment

Code Review

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

3 participants