feat(server/mcp): introduce generic client extension registry by duwenxin99 · Pull Request #3723 · googleapis/mcp-toolbox

duwenxin99 · 2026-07-27T20:33:59Z

Description

Added mcp.InitializeProtocols to orchestrate startup setup in internal/server/mcp, decoupling server.go from protocol-specific packages.
Add generic extension infra to the 20260728 mcp version.

PR Checklist

Make sure to open an issue as a bug/issue before writing your code!
Ensure the tests and linter pass
Code coverage does not decrease (if any source code was changed)
Appropriate docs were updated (if necessary)
Make sure to add ! if this involves a breaking change

Issue Reference
Fixes #0 🦕

gemini-code-assist

Code Review

This pull request introduces a generic client extensions utility to manage experimental MCP capabilities via context, replacing the hardcoded secure parameters check. It refactors GenerateListToolsResult and GenerateGetGroupResult to accept a context and use this utility. Additionally, the request handlers are updated to extract experimental capabilities from the request metadata and attach them to the context. The review feedback suggests optimizing extractClientExtensions to return nil instead of allocating an empty map when no experimental capabilities are present in the request metadata.

Yuan325

LGTM with some nit

github-actions · 2026-08-10T16:42:36Z

🧨 Preview deployments removed.

Cloudflare Pages environments for pr-3723 have been deleted.

…googleapis#3723) 1. Description - Added mcp.InitializeProtocols to orchestrate startup setup in internal/server/mcp, decoupling server.go from protocol-specific packages. - Add generic extension infra to the 20260728 mcp version. 2. PR Checklist - [x] Make sure to open an issue as a bug/issue before writing your code! - [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) - [ ] Make sure to add `!` if this involves a breaking change 3. Issue Reference Fixes #0 🦕 016245c

🤖 I have created a release *beep* *boop* --- ## [1.9.0](v1.8.0...v1.9.0) (2026-08-14) ### Features * **groups:** Add ttlMs and cacheScope customization to config ([#3805](#3805)) ([a5d4947](a5d4947)) * **migrate:** Convert toolset to group kind during migration ([#3704](#3704)) ([0adeaa5](0adeaa5)) * **server/mcp:** Introduce generic client extension registry ([#3723](#3723)) ([016245c](016245c)) * **skill:** Add review-prs skill for mcp-toolbox ([#3743](#3743)) ([5b7bacc](5b7bacc)) * **source/bigquery:** Add apiEndpoint field to override BigQuery API host ([#3437](#3437)) ([4da1600](4da1600)) * **source/databaseinsights:** Add databaseinsights source ([#3461](#3461)) ([3b9615d](3b9615d)) * **sources/spanner:** Rename execute_sql_dql to execute_sql_readonly ([#3776](#3776)) ([cf5a0c8](cf5a0c8)) * **tools/bigtable:** Add admin lifecycle and listing tools ([#3596](#3596)) ([801d589](801d589)) * **tools/bigtable:** Bigtable-list-schemas MCP tool ([#3683](#3683)) ([9228c61](9228c61)) * **tools/databaseinsights:** Add Advanced Query Insights tools for AlloyDB ([#3722](#3722)) ([74d18ae](74d18ae)) * **tools/looker:** Add additional tools to allow dashboards to be modified, and their layouts altered. ([#3597](#3597)) ([b2b80fb](b2b80fb)) * **tools:** Add cloud-sql-connect-gce for pg, mysql, mssql ([#3740](#3740)) ([ca58fa4](ca58fa4)) ### Bug Fixes * **auth/mcp:** Derive PRM URL from Toolbox URL ([#3765](#3765)) ([aa30842](aa30842)) * **config:** Ignore environment variables in YAML comments ([#3807](#3807)) ([79aa732](79aa732)), refs [#3793](#3793) * **mcp:** Return Tool execution error for invalid input param ([#3799](#3799)) ([8120197](8120197)) * **prebuilt/cloud-storage:** Declare tool collections as groups ([#3764](#3764)) ([7d468be](7d468be)) * **server/mcp:** Disallow client overriding URL bound parameters ([#3798](#3798)) ([f15a9c7](f15a9c7)) * **server:** Avoid a nil-flusher panic in the SSE handler ([#3520](#3520)) ([947f42f](947f42f)) * **tools/bigquery:** Keep the provider error classification in bigquery-execute-sql ([#3738](#3738)) ([42570b8](42570b8)) * **tools/looker:** Scope the filters quoting rule to values in query description ([#3788](#3788)) ([78eb0b8](78eb0b8)) * **util:** Convert exponent-form JSON numbers in ConvertNumbers ([#3730](#3730)) ([e9713ee](e9713ee)) --- 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* --- ## [1.9.0](v1.8.0...v1.9.0) (2026-08-14) ### Features * **groups:** Add ttlMs and cacheScope customization to config ([#3805](#3805)) ([a5d4947](a5d4947)) * **migrate:** Convert toolset to group kind during migration ([#3704](#3704)) ([0adeaa5](0adeaa5)) * **server/mcp:** Introduce generic client extension registry ([#3723](#3723)) ([016245c](016245c)) * **skill:** Add review-prs skill for mcp-toolbox ([#3743](#3743)) ([5b7bacc](5b7bacc)) * **source/bigquery:** Add apiEndpoint field to override BigQuery API host ([#3437](#3437)) ([4da1600](4da1600)) * **source/databaseinsights:** Add databaseinsights source ([#3461](#3461)) ([3b9615d](3b9615d)) * **sources/spanner:** Rename execute_sql_dql to execute_sql_readonly ([#3776](#3776)) ([cf5a0c8](cf5a0c8)) * **tools/bigtable:** Add admin lifecycle and listing tools ([#3596](#3596)) ([801d589](801d589)) * **tools/bigtable:** Bigtable-list-schemas MCP tool ([#3683](#3683)) ([9228c61](9228c61)) * **tools/databaseinsights:** Add Advanced Query Insights tools for AlloyDB ([#3722](#3722)) ([74d18ae](74d18ae)) * **tools/looker:** Add additional tools to allow dashboards to be modified, and their layouts altered. ([#3597](#3597)) ([b2b80fb](b2b80fb)) * **tools:** Add cloud-sql-connect-gce for pg, mysql, mssql ([#3740](#3740)) ([ca58fa4](ca58fa4)) ### Bug Fixes * **auth/mcp:** Derive PRM URL from Toolbox URL ([#3765](#3765)) ([aa30842](aa30842)) * **config:** Ignore environment variables in YAML comments ([#3807](#3807)) ([79aa732](79aa732)), refs [#3793](#3793) * **mcp:** Return Tool execution error for invalid input param ([#3799](#3799)) ([8120197](8120197)) * **prebuilt/cloud-storage:** Declare tool collections as groups ([#3764](#3764)) ([7d468be](7d468be)) * **server/mcp:** Disallow client overriding URL bound parameters ([#3798](#3798)) ([f15a9c7](f15a9c7)) * **server:** Avoid a nil-flusher panic in the SSE handler ([#3520](#3520)) ([947f42f](947f42f)) * **tools/bigquery:** Keep the provider error classification in bigquery-execute-sql ([#3738](#3738)) ([42570b8](42570b8)) * **tools/looker:** Scope the filters quoting rule to values in query description ([#3788](#3788)) ([78eb0b8](78eb0b8)) * **util:** Convert exponent-form JSON numbers in ConvertNumbers ([#3730](#3730)) ([e9713ee](e9713ee)) --- 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> 5de8f13

🤖 I have created a release *beep* *boop* --- ## [1.9.0](googleapis/mcp-toolbox@v1.8.0...v1.9.0) (2026-08-14) ### Features * **groups:** Add ttlMs and cacheScope customization to config ([googleapis#3805](googleapis#3805)) ([a5d4947](googleapis@a5d4947)) * **migrate:** Convert toolset to group kind during migration ([googleapis#3704](googleapis#3704)) ([0adeaa5](googleapis@0adeaa5)) * **server/mcp:** Introduce generic client extension registry ([googleapis#3723](googleapis#3723)) ([016245c](googleapis@016245c)) * **skill:** Add review-prs skill for mcp-toolbox ([googleapis#3743](googleapis#3743)) ([5b7bacc](googleapis@5b7bacc)) * **source/bigquery:** Add apiEndpoint field to override BigQuery API host ([googleapis#3437](googleapis#3437)) ([4da1600](googleapis@4da1600)) * **source/databaseinsights:** Add databaseinsights source ([googleapis#3461](googleapis#3461)) ([3b9615d](googleapis@3b9615d)) * **sources/spanner:** Rename execute_sql_dql to execute_sql_readonly ([googleapis#3776](googleapis#3776)) ([cf5a0c8](googleapis@cf5a0c8)) * **tools/bigtable:** Add admin lifecycle and listing tools ([googleapis#3596](googleapis#3596)) ([801d589](googleapis@801d589)) * **tools/bigtable:** Bigtable-list-schemas MCP tool ([googleapis#3683](googleapis#3683)) ([9228c61](googleapis@9228c61)) * **tools/databaseinsights:** Add Advanced Query Insights tools for AlloyDB ([googleapis#3722](googleapis#3722)) ([74d18ae](googleapis@74d18ae)) * **tools/looker:** Add additional tools to allow dashboards to be modified, and their layouts altered. ([googleapis#3597](googleapis#3597)) ([b2b80fb](googleapis@b2b80fb)) * **tools:** Add cloud-sql-connect-gce for pg, mysql, mssql ([googleapis#3740](googleapis#3740)) ([ca58fa4](googleapis@ca58fa4)) ### Bug Fixes * **auth/mcp:** Derive PRM URL from Toolbox URL ([googleapis#3765](googleapis#3765)) ([aa30842](googleapis@aa30842)) * **config:** Ignore environment variables in YAML comments ([googleapis#3807](googleapis#3807)) ([79aa732](googleapis@79aa732)), refs [googleapis#3793](googleapis#3793) * **mcp:** Return Tool execution error for invalid input param ([googleapis#3799](googleapis#3799)) ([8120197](googleapis@8120197)) * **prebuilt/cloud-storage:** Declare tool collections as groups ([googleapis#3764](googleapis#3764)) ([7d468be](googleapis@7d468be)) * **server/mcp:** Disallow client overriding URL bound parameters ([googleapis#3798](googleapis#3798)) ([f15a9c7](googleapis@f15a9c7)) * **server:** Avoid a nil-flusher panic in the SSE handler ([googleapis#3520](googleapis#3520)) ([947f42f](googleapis@947f42f)) * **tools/bigquery:** Keep the provider error classification in bigquery-execute-sql ([googleapis#3738](googleapis#3738)) ([42570b8](googleapis@42570b8)) * **tools/looker:** Scope the filters quoting rule to values in query description ([googleapis#3788](googleapis#3788)) ([78eb0b8](googleapis@78eb0b8)) * **util:** Convert exponent-form JSON numbers in ConvertNumbers ([googleapis#3730](googleapis#3730)) ([e9713ee](googleapis@e9713ee)) --- 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> 5de8f13

duwenxin99 requested a review from a team as a code owner July 27, 2026 20:34

blunderbuss-gcf Bot assigned Yuan325 Jul 27, 2026

gemini-code-assist Bot reviewed Jul 27, 2026

View reviewed changes

Comment thread internal/server/mcp/vdraft/method.go Outdated

duwenxin99 force-pushed the feat/generic-client-extensions branch from eb6ff62 to 947edc1 Compare July 27, 2026 20:35

duwenxin99 changed the base branch from feat/secure-param-draft-mcp to main July 27, 2026 20:36

duwenxin99 changed the title ~~refactor(server/mcp): introduce generic client extension registry~~ feat(server/mcp): introduce generic client extension registry Jul 27, 2026

Yuan325 reviewed Jul 28, 2026

View reviewed changes

Comment thread internal/server/mcp/v20260728/extensions.go Outdated

duwenxin99 force-pushed the feat/generic-client-extensions branch from c52751a to c402618 Compare July 30, 2026 19:33

Yuan325 reviewed Aug 3, 2026

View reviewed changes

Comment thread internal/server/mcp/v20260728/extensions.go Outdated

Yuan325 requested changes Aug 4, 2026

View reviewed changes

duwenxin99 force-pushed the feat/generic-client-extensions branch 2 times, most recently from ea11341 to 826c331 Compare August 5, 2026 22:51

versioned extension support

5cc22c3

duwenxin99 force-pushed the feat/generic-client-extensions branch from 826c331 to 5cc22c3 Compare August 5, 2026 22:51

duwenxin99 added 2 commits August 5, 2026 19:13

update tests

e38118f

fix nit;

ec94123

Yuan325 approved these changes Aug 6, 2026

View reviewed changes

Comment thread internal/server/mcp/v20260728/extensions.go Outdated

Comment thread internal/server/mcp/v20260728/extensions.go

duwenxin99 and others added 3 commits August 6, 2026 16:46

resolve comments

4fe2156

fix test

effea1d

Merge branch 'main' into feat/generic-client-extensions

cd34dec

duwenxin99 enabled auto-merge (squash) August 10, 2026 15:37

duwenxin99 merged commit 016245c into main Aug 10, 2026
25 checks passed

duwenxin99 deleted the feat/generic-client-extensions branch August 10, 2026 16:42

release-please Bot mentioned this pull request Aug 10, 2026

chore(main): release 1.9.0 #3744

Merged

BrewTestBot mentioned this pull request Aug 14, 2026

mcp-toolbox 1.9.0 Homebrew/homebrew-core#298753

Merged

Navigation Menu

Uh oh!

feat(server/mcp): introduce generic client extension registry - #3723

feat(server/mcp): introduce generic client extension registry#3723
duwenxin99 merged 6 commits into
mainfrom
feat/generic-client-extensions

duwenxin99 commented Jul 27, 2026 •

edited

Loading

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!

Uh oh!

Uh oh!

Uh oh!

Yuan325 left a comment •

edited

Loading

Uh oh!

Uh oh!

Uh oh!

Uh oh!

github-actions Bot commented Aug 10, 2026

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

2 participants

Uh oh!

Conversation

duwenxin99 commented Jul 27, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

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!

Uh oh!

Uh oh!

Uh oh!

Yuan325 left a comment • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Uh oh!

Uh oh!

Uh oh!

github-actions Bot commented Aug 10, 2026

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

2 participants

duwenxin99 commented Jul 27, 2026 •

edited

Loading

Yuan325 left a comment •

edited

Loading