fix: default Anthropic tool_use input to {} when arguments are absent

[impoiler]

Summary

Anthropic's API requires the input field to always be present on tool_use blocks. When a tool takes no arguments, the field was previously left unset, causing API errors. This PR ensures input defaults to an empty JSON object ({}) in those cases.

Changes

• In convertBifrostFunctionCallToAnthropicToolUse, convertBifrostMCPCallToAnthropicToolUse, and convertBifrostMCPApprovalToAnthropicToolUse, added an else branch that sets toolUseBlock.Input to json.RawMessage("{}") when no arguments are provided.

Type of change

• Bug fix
• Feature
• Refactor
• Documentation
• Chore/CI

Affected areas

• Core (Go)
• Transports (HTTP)
• Providers/Integrations
• Plugins
• UI (React)
• Docs

How to test

Send a tool call to the Anthropic provider where the tool accepts no arguments (i.e., arguments are nil or an empty string). Verify the request succeeds and the resulting tool_use block contains "input": {} rather than an absent or null input field.

go test ./...

Breaking changes

• Yes
• No

Related issues

Security considerations

None.

Checklist

• I read docs/contributing/README.md and followed the guidelines
• I added/updated tests where appropriate
• I updated documentation where needed
• I verified builds succeed (Go and UI)
• I verified the CI pipeline passes locally if applicable

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[impoiler]

• fix: default Anthropic tool_use input to {} when arguments are absent #3880 👈 (View in Graphite)
• fix: responses stream events #3838
• dev

This stack of pull requests is managed by Graphite. Learn more about stacking.

[greptile-apps]

Confidence Score: 5/5

Safe to merge — the change is a targeted, pure-transformation fix that adds no side effects and is covered by new table-driven tests.

The fix is minimal and correct: all three converters are pure transformation functions, the new else-branch mirrors what parseJSONInput would return for an empty string anyway, and the added tests directly exercise all three argument states.

No files require special attention.

Important Files Changed

Filename	Overview
core/providers/anthropic/responses.go	Adds else branch in three converter functions to default toolUseBlock.Input to json.RawMessage("{}") when arguments are nil or empty, satisfying Anthropic's API requirement that input always be present on tool_use blocks.
core/providers/anthropic/toolinput_test.go	New table-driven tests for all three converter functions, covering nil arguments, empty arguments, and populated arguments — directly pins the fix introduced in this PR.

_{Reviews (3): Last reviewed commit: "fix: placeholder for tool arguments in A..." | Re-trigger Greptile}

[akshaydeo]

Merge activity

• May 29, 12:30 PM UTC: A user started a stack merge that includes this pull request via Graphite.
• May 29, 12:31 PM UTC: @akshaydeo merged this pull request with Graphite.