Anthropic/claude tool response and javascript asse...
# questionst
tak2406
09/05/2025, 2:44 PMI'm trying to write a javascript assert for an anthropic tool response; but I don't seem to get the output var, tried many things, is there someone with a working example?
w
Will [Promptfoo]
09/05/2025, 3:32 PMCan you share your config?
t
tak2406
09/17/2025, 2:34 PMthe below javascript assert only works for openai, not for anthropic; the output is tool output and correct in both cases, it just seems that the assert doesn't get the anthropic output at all
providers:
- id: anthropic:claude-sonnet-4-20250514
config:
tools: file://./extract-anthropic.json
tool_choice:
type: 'tool'
name: 'extract_document_data'
- id: openai:gpt-4o
config:
tools: file://./extract.json
tool_choice: 'required'
tests:
- vars:
ocr_text: file://./data*.txt
assert:
- type: javascript
value: JSON.parse(output[0].function.arguments).issue_date.value === "2025-08-25"
tak2406
09/17/2025, 2:34 PMERROR:
Custom function threw error: Cannot read properties of undefined (reading 'arguments')
Stack Trace: TypeError: Cannot read properties of undefined (reading 'arguments')
at eval (eval at handleJavascript (/Users/tomvleminckx/.npm/_npx/81bbc6515d992ace/node_modules/promptfoo/dist/src/assertions/javascript.js:49:36), :3:38)
at handleJavascript (/Users/tomvleminckx/.npm/_npx/81bbc6515d992ace/node_modules/promptfoo/dist/src/assertions/javascript.js:50:43)
at runAssertion (/Users/tomvleminckx/.npm/_npx/81bbc6515d992ace/node_modules/promptfoo/dist/src/assertions/index.js:313:30)
at /Users/tomvleminckx/.npm/_npx/81bbc6515d992ace/node_modules/promptfoo/dist/src/assertions/index.js:360:30
at /Users/tomvleminckx/.npm/_npx/81bbc6515d992ace/node_modules/promptfoo/node_modules/async/dist/async.js:151:38
at replenish (/Users/tomvleminckx/.npm/_npx/81bbc6515d992ace/node_modules/promptfoo/node_modules/async/dist/async.js:447:21)
at iterateeCallback (/Users/tomvleminckx/.npm/_npx/81bbc6515d992ace/node_modules/promptfoo/node_modules/async/dist/async.js:431:21)
at /Users/tomvleminckx/.npm/_npx/81bbc6515d992ace/node_modules/promptfoo/node_modules/async/dist/async.js:328:20
at invokeCallback (/Users/tomvleminckx/.npm/_npx/81bbc6515d992ace/node_modules/promptfoo/node_modules/async/dist/async.js:182:13)
at /Users/tomvleminckx/.npm/_npx/81bbc6515d992ace/node_modules/promptfoo/node_modules/async/dist/async.js:174:13
JSON.parse(output[0].function.arguments).issue_date.value === "2025-08-25"
{"type":"tool_use","id":"toolu_01LjkyRza6ZPLHxe5GJyCKgW","name":"extract_document_data","input":{"issue_date":{"value":"2025-08-25","coordinates":{"x":339,"y":314,"width":142,"height":17,"page_number":1}},"ca_type":{"value":"Takeover","coordinates":{"x":340,"y":548,"width":84,"height":14,"page_number":1}}}}
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a
Alan [Promptfoo]
09/17/2025, 5:21 PMtry
type: javascript
value: |
const toolData = output[0].function?.arguments || output[0].input;
return JSON.parse(typeof toolData === 'string' ? toolData : JSON.stringify(toolData))
.issue_date.value === "2025-08-25";
t
tak2406
09/18/2025, 7:57 AMthanks for the reply; it seems that output is undefined in the anthorpic case; so the suggested solution doesn't work