Fix Google VertexAI chat completion tool call args for non-string values by seanhandley · Pull Request #156665 · elastic/elasticsearch

seanhandley · 2026-08-13T09:59:12Z

Summary

GoogleVertexAiUnifiedChatCompletionRequestEntity#jsonStringToMap used parser.mapStrings() which calls parser.text() on each map value. When a tool call argument value is a JSON array, number, or nested object (e.g. {"indices": ["foo"]}) the parser throws Expected text but found START_ARRAY.

Change parser.mapStrings() → parser.map() (returning Map<String, Object>) so arbitrary JSON argument values are preserved and serialized correctly into the Vertex AI functionCall.args Struct field.

Changes

GoogleVertexAiUnifiedChatCompletionRequestEntity.java: one-line change — mapStrings() → map(), return type Map<String,String> → Map<String,Object>
GoogleVertexAiUnifiedChatCompletionRequestEntityTests.java: adds testParseFunctionCallWithNonStringArgValues covering array and number argument values

Test plan

./gradlew :x-pack:plugin:inference:test --tests "org.elasticsearch.xpack.inference.services.googlevertexai.request.completion.GoogleVertexAiUnifiedChatCompletionRequestEntityTests"
Existing testParseFunctionCallWithBadJson still expects ParsingException for non-object top-level JSON (unchanged behaviour)

🤖 Generated with Claude Code

jsonStringToMap used parser.mapStrings() which calls parser.text() on each value, throwing when the value is an array or number. Change to parser.map() so arbitrary JSON argument values are preserved correctly when serialized into the Vertex AI functionCall.args Struct field.

github-actions · 2026-08-13T10:02:47Z

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elasticsearchmachine · 2026-08-13T10:03:24Z

Pinging @elastic/search-inference-team (Team:Search - Inference)

github-actions · 2026-08-13T10:04:27Z

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Pull request overview

Fixes Google VertexAI chat_completion request serialization for tool calls whose arguments JSON contains non-string values (arrays, numbers, nested objects). This aligns the request builder with the OpenAI-compatible tool-calling spec and prevents request construction failures before the request is sent to Vertex AI.

Changes:

Parse tool-call arguments JSON with XContentParser#map() instead of mapStrings(), preserving non-string values.
Update the jsonStringToMap return type to Map<String, Object> accordingly.
Add a unit test covering array and numeric argument values to prevent regressions.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
x-pack/plugin/inference/src/main/java/org/elasticsearch/xpack/inference/services/googlevertexai/request/completion/GoogleVertexAiUnifiedChatCompletionRequestEntity.java	Switch tool-call args parsing from string-only maps to generic maps so arrays/numbers/objects serialize correctly.
x-pack/plugin/inference/src/test/java/org/elasticsearch/xpack/inference/services/googlevertexai/request/completion/GoogleVertexAiUnifiedChatCompletionRequestEntityTests.java	Add regression test validating serialization of tool-call args containing arrays and numbers.
docs/changelog/156644.yaml	Add changelog entry documenting the bug fix.

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dimitris-athanasiou

LGTM

dimitris-athanasiou · 2026-08-13T10:11:43Z

Let's backport this to 9.5, 9.4, and 8.19. I'll add the labels.

…-156644

seanhandley · 2026-08-13T16:06:28Z

Skipped the flaky serverless check and merged

jonathan-buttner · 2026-08-13T16:24:14Z

💚 All backports created successfully

Status	Branch	Result
✅	9.5
✅	9.4
✅	8.19

Questions ?

Please refer to the Backport tool documentation

…ues (#156665) (#156699) * Fix Google VertexAI tool call args serialization for non-string values jsonStringToMap used parser.mapStrings() which calls parser.text() on each value, throwing when the value is an array or number. Change to parser.map() so arbitrary JSON argument values are preserved correctly when serialized into the Vertex AI functionCall.args Struct field. * Fix changelog area for 156644 (cherry picked from commit 35d2cca) Co-authored-by: Sean Handley <seanhandley@users.noreply.github.com>

…ing values (#156665) (#156701) * Fix Google VertexAI chat completion tool call args for non-string values (#156665) * Fix Google VertexAI tool call args serialization for non-string values jsonStringToMap used parser.mapStrings() which calls parser.text() on each value, throwing when the value is an array or number. Change to parser.map() so arbitrary JSON argument values are preserved correctly when serialized into the Vertex AI functionCall.args Struct field. * Fix changelog area for 156644 (cherry picked from commit 35d2cca) * Fixing class ref --------- Co-authored-by: Sean Handley <seanhandley@users.noreply.github.com>

The entry recorded pr: 156644, but 156644 is the issue number. The change was made by PR #156665, backported here as #156699. Point pr: at the PR and leave the issue reference intact. Previously the note rendered a link to /pull/156644 alongside a self-referencing "(issue: #156644)". This affects the 9.5.2 release notes, which are bundled from this branch. The filename is deliberately left as 156644.yaml rather than renamed to match the PR: the 9.5.2 build candidate is cut from this branch today, and BundleChangelogsTask adds changelogs from branch HEAD on top of the BC tree without deleting removed files, so a rename after the BC would list this fix twice in the release notes.

…ues (#156665) (#156700) * Fix Google VertexAI tool call args serialization for non-string values jsonStringToMap used parser.mapStrings() which calls parser.text() on each value, throwing when the value is an array or number. Change to parser.map() so arbitrary JSON argument values are preserved correctly when serialized into the Vertex AI functionCall.args Struct field. * Fix changelog area for 156644 (cherry picked from commit 35d2cca) Co-authored-by: Sean Handley <seanhandley@users.noreply.github.com>

…ues (elastic#156665) * Fix Google VertexAI tool call args serialization for non-string values jsonStringToMap used parser.mapStrings() which calls parser.text() on each value, throwing when the value is an array or number. Change to parser.map() so arbitrary JSON argument values are preserved correctly when serialized into the Vertex AI functionCall.args Struct field. * Fix changelog area for 156644

elasticsearchmachine added v9.6.0 needs:triage Requires assignment of a team area label labels Aug 13, 2026

seanhandley force-pushed the fix/googlevertexai-tool-call-non-string-args-156644 branch from e7ef0ec to 3cd73e2 Compare August 13, 2026 10:01

seanhandley added :SearchOrg/Inference Label for the Search Inference team Team:Search - Inference labels Aug 13, 2026

seanhandley added the >bug label Aug 13, 2026

seanhandley self-assigned this Aug 13, 2026

seanhandley requested a lite review from Copilot August 13, 2026 10:03

elasticsearchmachine removed the needs:triage Requires assignment of a team area label label Aug 13, 2026

Copilot started reviewing on behalf of seanhandley August 13, 2026 10:03 View session

seanhandley requested a review from dimitris-athanasiou August 13, 2026 10:04

Copilot AI reviewed Aug 13, 2026

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dimitris-athanasiou approved these changes Aug 13, 2026

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dimitris-athanasiou added auto-backport Automatically create backport pull requests when merged v8.19.21 v9.4.6 v9.5.2 labels Aug 13, 2026

seanhandley and others added 2 commits August 13, 2026 11:20

Merge branch 'main' into fix/googlevertexai-tool-call-non-string-args…

4e194c1

…-156644

Fix changelog area for 156644

3aa3f58

seanhandley enabled auto-merge (squash) August 13, 2026 10:36

chrisbmar mentioned this pull request Aug 13, 2026

[inference] Sanitize tool schemas for Google Vertex AI inference endpoints elastic/kibana#284810

Merged

seanhandley added 2 commits August 13, 2026 13:43

Merge branch 'main' into fix/googlevertexai-tool-call-non-string-args…

f8c21e3

…-156644

Merge branch 'main' into fix/googlevertexai-tool-call-non-string-args…

9993e20

…-156644

seanhandley disabled auto-merge August 13, 2026 16:05

seanhandley merged commit 35d2cca into main Aug 13, 2026
37 of 38 checks passed

seanhandley deleted the fix/googlevertexai-tool-call-non-string-args-156644 branch August 13, 2026 16:06

This was referenced Aug 13, 2026

[9.5] Fix Google VertexAI chat completion tool call args for non-string values (#156665) #156699

Merged

[9.4] Fix Google VertexAI chat completion tool call args for non-string values (#156665) #156700

Merged

jonathan-buttner mentioned this pull request Aug 13, 2026

[8.19] Fix Google VertexAI chat completion tool call args for non-string values (#156665) #156701

Merged

This was referenced Aug 18, 2026

Fix PR reference in 156644 changelog entry #157036

Merged

[9.5] Fix PR reference in 156644 changelog entry #157037

Merged

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Fix Google VertexAI chat completion tool call args for non-string values - #156665

Fix Google VertexAI chat completion tool call args for non-string values#156665
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seanhandley commented Aug 13, 2026

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