fix: normalize toolCall arguments to prevent Anthropic API rejection by manzienkog · Pull Request #2213 · openclaw/openclaw

manzienkog · 2026-01-26T12:38:54Z

Problem

Some models (e.g., via google-antigravity) omit the arguments field for tools with no required parameters. When this happens, pi-ai passes undefined to Anthropic's input field, causing API rejection:

messages.N.content.M.tool_use.input: Field required

Solution

Added normalizeToolCallArguments() which ensures arguments is always an object (defaulting to {}) before messages reach the API.

Affected tools

memory_status
load_memory (without trigger)
Any tool with optional-only or no parameters

Testing

Added tests in tool-call-id.test.ts covering:

Already-present arguments (no-op)
Undefined arguments → {}
Null arguments → {}
Multiple toolCalls in single message
Different tool types (toolCall, toolUse, functionCall)
Non-assistant messages unchanged

Greptile Overview

Greptile Summary

This PR adds normalizeToolCallArguments() to ensure assistant tool-call blocks always have an object-valued arguments field (defaulting missing/null to {}), preventing downstream providers (notably Anthropic) from rejecting messages where tool input is required but omitted by upstream models. The normalization is exported via pi-embedded-helpers and applied in the Google transcript sanitization pipeline (sanitizeSessionHistory), and a dedicated vitest suite is added to validate behavior across tool block types and message roles.

Confidence Score: 4/5

This PR is largely safe to merge and should fix the reported provider rejection scenario.
Changes are small and localized (pure normalization + wiring + tests). The main risk is scope/semantics (normalizing tool-call arguments for all providers) and a slightly misleading comment; no functional regressions were evident from code inspection, but I couldn’t run the test suite in this environment (pnpm unavailable).
src/agents/pi-embedded-runner/google.ts (ensure the intended scope of normalization/comment matches behavior)

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Some models (e.g., via google-antigravity) omit the 'arguments' field for tools with no required parameters. When this happens, pi-ai passes undefined to Anthropic's 'input' field, causing API rejection with: 'messages.N.content.M.tool_use.input: Field required' This fix adds normalizeToolCallArguments() which ensures arguments is always an object (defaulting to {}) before messages reach the API. Fixes tool calls for: - memory_status - load_memory (without trigger) - Any tool with optional-only or no parameters

ChiTienHsieh · 2026-01-27T19:19:00Z

We hit this exact bug running clawdbot v2026.1.24-3 with Google Antigravity on a Hetzner VPS and spent time tracing the root cause on our end. Confirming the fix is correct.

Root cause trace

Ingestion — google-gemini-cli.js:532:
```
arguments: part.functionCall.args
```
For zero-arg tools like session_status, args is undefined. The property gets stripped by JSON serialization, so session JSONL stores the block without an arguments key at all.
Replay — anthropic.js:470:
```
input: block.arguments
```
block.arguments is undefined → stripped by JSON.stringify → Anthropic API rejects with tool_use.input: Field required. Session is permanently broken until /reset.

Assessment

PR #2213's normalizeToolCallArguments is the right defensive fix at the replay/sanitization stage. Clean implementation, good test coverage, correct pipeline placement.

Suggestion: Consider also adding ?? {} at the ingestion point (google-gemini-cli.js:532) so corrupted sessions aren't written in the first place — belt-and-suspenders.

Grade: A. Ship it.

Investigated hands-on from a VM running clawdbot with Antigravity — session JSONL confirmed missing arguments key on zero-arg tool calls.

greptile-apps

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greptile-apps · 2026-02-03T03:57:47Z

src/agents/pi-embedded-runner/google.ts


+  // Normalize toolCall arguments to ensure they're always an object.
+  // Some models omit `arguments` for tools with no required params,
+  // but Anthropic API requires `input` to be present.
+  const normalizedArgs = normalizeToolCallArguments(repairedTools);


[P3] Comment mentions Anthropic, but this normalization runs unconditionally

sanitizeSessionHistory always applies normalizeToolCallArguments regardless of provider/model (google, openai-responses, etc.). The comment at google.ts:340-343 says “Anthropic API requires input”, which is true for the reported failure, but it’s misleading in this location since the logic isn’t Anthropic-specific; consider rewording to reflect that we’re normalizing transcript/tool-call shape for downstream consumers/providers in general.

_{Note: If this suggestion doesn't match your team's coding style, reply to this and let me know. I'll remember it for next time!}

Prompt To Fix With AI

This is a comment left during a code review. Path: src/agents/pi-embedded-runner/google.ts Line: 339:343 Comment: [P3] Comment mentions Anthropic, but this normalization runs unconditionally `sanitizeSessionHistory` always applies `normalizeToolCallArguments` regardless of provider/model (`google`, `openai-responses`, etc.). The comment at `google.ts:340-343` says “Anthropic API requires `input`”, which is true for the reported failure, but it’s misleading in this location since the logic isn’t Anthropic-specific; consider rewording to reflect that we’re normalizing transcript/tool-call shape for downstream consumers/providers in general. <sub>Note: If this suggestion doesn't match your team's coding style, reply to this and let me know. I'll remember it for next time!</sub> How can I resolve this? If you propose a fix, please make it concise.

vignesh07 · 2026-02-12T20:29:55Z

Thanks for the careful fix and clear context.

We’re closing this PR because malformed tool-call handling has since been addressed in later updates on main, so this exact change is now superseded.

Really appreciate the contribution.

sebslight added gateway Gateway runtime and removed gateway Gateway runtime labels Jan 26, 2026

This was referenced Feb 2, 2026

fix(session): strip malformed tool_use blocks to prevent session corruption #5557

Closed

fix(agents): skip extracting tool calls from errored assistant turns #1859

Closed

greptile-apps bot reviewed Feb 3, 2026

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vignesh07 closed this Feb 12, 2026

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Comments

fix: normalize toolCall arguments to prevent Anthropic API rejection#2213

fix: normalize toolCall arguments to prevent Anthropic API rejection#2213
manzienkog wants to merge 1 commit intoopenclaw:mainfrom
manzienkog:main

manzienkog commented Jan 26, 2026 •

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Problem

Solution

Affected tools

Testing

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Confidence Score: 4/5

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ChiTienHsieh commented Jan 27, 2026

Root cause trace

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manzienkog commented Jan 26, 2026 •

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