Request without tools definition.
Problem
Error code: 400 - {'type': 'error', 'error': {'type': 'invalid_request_error', 'message': 'Requests which include tool_use or tool_result blocks must define tools.'}} I believe this issue could be better addressed directly to the Anthropic Server Team, but I have not found a way to report this issue directly. When interacting with the Anthropic API, my initial request includes the necessary tool definitions, which are processed correctly. However, for certain reasons, I need to remove the tool definitions after responding to the assistant's tool_use request appropriately. Subsequent messages sent to the Anthropic API without tool definitions then trigger the error mentioned above. It is a common scenario to toggle between states where tools are either provided or not, as sometimes it is necessary to manually avoid unintended tool invocations. The simplest method is not to include tool definitions when they are not needed. However, the current design of the API seems to require that once tools have been invoked, all subsequent requests must include tool definitions. This requirement seems unreasonable. We hope that Anthropic will consider this use case and make necessary adjustments.
Error Output
Error code: 400 - {'type': 'error', 'error': {'type': 'invalid_request_error', 'message': 'Requests which include tool_use or tool_result blocks must define tools.'}}
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1 Fix
Ensure Tool Definitions are Included After Tool Invocation
The Anthropic API requires that once a tool has been invoked in a session, all subsequent requests must include the tool definitions. This design choice leads to errors when requests that reference tool usage or results are sent without the necessary tool definitions, causing a 400 error response.
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- 1
Capture Tool Definitions
Before making any requests that include tool usage, ensure that you capture the tool definitions in a variable. This will allow you to resend them in subsequent requests as needed.
javascriptconst toolDefinitions = [{ name: 'tool1', description: 'This is tool 1' }, { name: 'tool2', description: 'This is tool 2' }]; - 2
Modify Request Logic
Adjust your request logic to always include the tool definitions in any API call that references tool usage or results. This can be done by checking if the previous request involved tool usage and conditionally appending the tool definitions.
javascriptconst requestPayload = { ...basePayload, tools: toolDefinitions }; - 3
Implement State Management
Create a state management system that tracks whether tools have been invoked. Use this state to determine if tool definitions should be included in future requests.
javascriptlet toolsInvoked = false; // Set to true when a tool is invoked if (toolsInvoked) { requestPayload.tools = toolDefinitions; } - 4
Test API Requests
After implementing the above changes, conduct tests by sending requests to the Anthropic API that include tool usage and ensure that tool definitions are included. Monitor for any 400 errors related to missing tool definitions.
javascriptfetch('https://api.anthropic.com/v1/your-endpoint', { method: 'POST', body: JSON.stringify(requestPayload) });
Validation
Confirm that subsequent requests to the Anthropic API do not return a 400 error when tool usage is involved. Monitor the responses for successful processing of tool requests.
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Environment
Submitted by
Alex Chen
2450 rep