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Issue: Empty Arguments in Tool Call Despite Requir...
# support
r
Issue where the assistant is making tool calls with empty arguments (
{}
) despite the tool having required parameters with strict validation. Interestingly, this only happens with one specific tool while another similar tool works perfectly. ## What's Working - 
appointment_timeslots_tool
works correctly - the AI provides all required parameters - The tool has 5 required parameters (ZipCode, Address, City, Phone, Email) - The AI correctly fills these parameters based on the conversation ## What's Not Working - 
appointment_creation_tool
consistently receives empty arguments 
{}
- The tool has 11 required parameters (CorrelationID, FirstName, LastName, etc.) - Despite having all the information from the conversation and previous tool call, the AI sends 
arguments: {}
## Logs and Behavior - First tool call (works): 
"arguments": {"ZipCode": "75001", "Address": "456 Oak Street", ...}
- Second tool call (fails): 
"arguments": {}
- I've tried simplifying the parameter structure to avoid nested objects, but the issue persists - I've verified the AI has all the necessary information to fill in the parameters Any assistance would be greatly appreciated!
v
Suggestion: Double-check the 
parameters
definition for your 
appointment_creation_tool
in your tool configuration. Make sure each required parameter is explicitly listed and not nested, and that the tool's 
strict
property is set to 
true
. For example:
Copy code
json
{
  "type": "function",
  "function": {
    "name": "appointment_creation_tool",
    "strict": true,
    "parameters": {
      "type": "object",
      "properties": {
        "CorrelationID": { "type": "string" },
        "FirstName": { "type": "string" },
        "LastName": { "type": "string" }
        // ...add all required fields
      },
      "required": ["CorrelationID", "FirstName", "LastName" /* ... */]
    }
  }
}
After updating, re-deploy and test. This ensures the AI knows exactly which fields to fill and avoids empty argument payloads. Sources: - [Custom Tools Documentation](https://docs.vapi.ai/tools/custom-tools) - [Prompting Guide](https://docs.vapi.ai/prompting-guide)
p
Hey! To help track down this issue, could you share: - The call ID
r
Here's the call ID and additional context: **Call ID**: 
call_GSQbLnNxGAgB7zhaQSo8pZcx
**Timestamp**: 2025-05-21 14:19:09.265 (Started At) - 2025-05-21 14:19:11.680 (Finished At) **The Actual Issue**: Looking at this specific call, the AI sent most parameters but missed 2 required parameters despite having 
strict: true
validation: - Missing: 
State
(required) - Missing: 
RepID
(required) The tool definition clearly shows 11 required parameters: 
["CorrelationID", "FirstName", "LastName", "Phone", "Email", "Address", "City", "State", "ZipCode", "AppointmentDateTime", "RepID"]
But the AI only sent 10 parameters, omitting 
State
and 
RepID
. **Model Behavior**: Initially discovered this issue was worse with Claude 3.7 Sonnet (would send completely empty arguments 
{}
), but after switching to OpenAI's model, I found it still occasionally misses required parameters despite 
strict: true
validation. **Critical Issue**: This problem is compounded by the fact that when I send error responses back to the AI (like "ERROR: Missing required parameters: State, RepID"), the AI agent doesn't receive these messages (linked issue: https://discord.com/channels/1211482211119796234/1374830137845092455). So the AI has no way to know it made an incomplete tool call and can't self-correct. These two issues combined make the platform extremely unreliable - the strict validation isn't working, and error feedback doesn't reach the AI.
Here's another call ID showing the original Claude issue: **Call ID**: 
toolu_011yxevzp3VrHYsf9BgYETQ2
This call demonstrates the Claude 3.7 Sonnet problem - completely empty arguments 
{}
 despite having 11 required parameters and 
strict: true
validation:
Copy code
json
"function": {
  "name": "appointment_creation_tool", 
  "arguments": {}
}
p
Hi @rpv, sorry for the confusion but that looks like a toolCallId for the tool and not the whole call. If you would like to find the call id for the specific call, you can locate it on the dashboard here in the call logs page. Once we get that information, we can proceed the investigation. https://cdn.discordapp.com/attachments/1374732868843995237/1375273722080137338/call_id.png?ex=683116f6&is=682fc576&hm=c51f0f82c7a5b49fe0a6ae330e796f648ae602f21b7f17edb5ef66db6f590a68&
r
- __Tool Call ID__: 
call_4jRGUjRFivxyf75J3Uu2eoBh
- __Vapi Call ID__: 
77c764ef-deb5-481b-a8b0-646a1fc2a730
This is the call where the AI was missing the 
Email
parameter despite 
strict: true
validation, and where the error response wasn't reaching the AI.
v
Suggestion: Double-check your 
appointment_creation_tool
configuration to ensure all required parameters are explicitly listed (not nested) and included in the 
required
array, with 
"strict": true
set. For example:
Copy code
json
{
  "type": "function",
  "function": {
    "name": "appointment_creation_tool",
    "strict": true,
    "parameters": {
      "type": "object",
      "properties": {
        "CorrelationID": { "type": "string" },
        "FirstName": { "type": "string" },
        "LastName": { "type": "string" }
        // ...add all required fields
      },
      "required": ["CorrelationID", "FirstName", "LastName" /* ... */]
    }
  }
}
After updating, redeploy and test. Note: If error responses aren't reaching the AI for self-correction, this is a known limitation—consider raising a support ticket if this is critical for your workflow. Sources: [Custom Tools Documentation](https://docs.vapi.ai/tools/custom-tools), [Prompting Guide](https://docs.vapi.ai/prompting-guide) Sources: - [Custom Tools Documentation](https://docs.vapi.ai/tools/custom-tools) - [Prompting Guide](https://docs.vapi.ai/prompting-guide)
p
Hey @rpv, checking if this is resolved/solved for you?
r
No, I need help and clarification, in this call for example 
d08a2eb6-ee9a-4680-893b-886c16ce4362
you can see how the appointment_timeslots tool works but the appointment_creation tool is not working, even when I have strict parameters validation and I'm sending back and error message with the missing required parameters:
Copy code
"result": "ERROR: Missing required parameters for appointment creation. Please provide CorrelationID, FirstName, LastName, Phone, Email, Address, City, State, ZipCode, AppointmentDateTime, and RepID.",
      "toolCallId": "toolu_01PLcH3akcpcY7CDtcPjGDHD"
v
Thank you for the detailed information. Since your configuration appears correct and the issue persists even after following all standard troubleshooting steps, have you already submitted a formal support ticket to Vapi regarding this unresolved validation and error feedback problem? If not, would you like guidance on how to do so? Sources: - [Custom Tools Documentation](https://docs.vapi.ai/tools/custom-tools) - [Prompting Guide](https://docs.vapi.ai/prompting-guide)
Thank you for the detailed information. Since your configuration appears correct and the issue persists even after following all standard troubleshooting steps, have you already submitted a formal support ticket to Vapi regarding this unresolved validation and error feedback problem? If not, would you like guidance on how to do so? Sources: - [Custom Tools Documentation](https://docs.vapi.ai/tools/custom-tools) - [Prompting Guide](https://docs.vapi.ai/prompting-guide)
Actionable Next Step: Double-check that your 
appointment_creation_tool
configuration explicitly lists all required parameters (no nesting) and that 
"strict": true
is set. Here’s a sample structure:
Copy code
json
{
  "type": "function",
  "function": {
    "name": "appointment_creation_tool",
    "strict": true,
    "parameters": {
      "type": "object",
      "properties": {
        "CorrelationID": { "type": "string" },
        "FirstName": { "type": "string" },
        "LastName": { "type": "string" },
        "Phone": { "type": "string" },
        "Email": { "type": "string" },
        "Address": { "type": "string" },
        "City": { "type": "string" },
        "State": { "type": "string" },
        "ZipCode": { "type": "string" },
        "AppointmentDateTime": { "type": "string" },
        "RepID": { "type": "string" }
      },
      "required": [
        "CorrelationID", "FirstName", "LastName", "Phone", "Email",
        "Address", "City", "State", "ZipCode", "AppointmentDateTime", "RepID"
      ]
    }
  }
}
After updating, redeploy and test. If the issue persists and error feedback is not reaching the AI, consider raising a support ticket, as this is a known platform limitation. [Custom Tools Documentation](https://docs.vapi.ai/tools/custom-tools) Sources: - [Custom Tools Documentation](https://docs.vapi.ai/tools/custom-tools) - [Prompting Guide](https://docs.vapi.ai/prompting-guide)
Actionable Next Step: Double-check that your 
appointment_creation_tool
configuration explicitly lists all required parameters (no nesting) and that 
"strict": true
is set. Here’s a sample structure:
Copy code
json
{
  "type": "function",
  "function": {
    "name": "appointment_creation_tool",
    "strict": true,
    "parameters": {
      "type": "object",
      "properties": {
        "CorrelationID": { "type": "string" },
        "FirstName": { "type": "string" },
        "LastName": { "type": "string" },
        "Phone": { "type": "string" },
        "Email": { "type": "string" },
        "Address": { "type": "string" },
        "City": { "type": "string" },
        "State": { "type": "string" },
        "ZipCode": { "type": "string" },
        "AppointmentDateTime": { "type": "string" },
        "RepID": { "type": "string" }
      },
      "required": [
        "CorrelationID", "FirstName", "LastName", "Phone", "Email",
        "Address", "City", "State", "ZipCode", "AppointmentDateTime", "RepID"
      ]
    }
  }
}
After updating, redeploy and test. If the issue persists and error feedback is not reaching the AI, consider raising a support ticket, as this is a known platform limitation. [Custom Tools Documentation](https://docs.vapi.ai/tools/custom-tools) Sources: - [Custom Tools Documentation](https://docs.vapi.ai/tools/custom-tools) - [Prompting Guide](https://docs.vapi.ai/prompting-guide)
r
How can I open a formal support ticket?
v
To open a formal support ticket with Vapi, simply email your issue details (including call IDs, error logs, and a description of the problem) to support@vapi.ai. This is the primary method for submitting support requests. For real-time help, you can also join the [Vapi Discord community](https://discord.com/invite/pUFNcf2WmH) and post in the #support channel. Example:
Copy code
To: support@vapi.ai
Subject: Tool Call Validation Issue - appointment_creation_tool

[Describe your issue, include call IDs, error logs, and steps to reproduce.]
Source: - [Vapi Support Documentation](https://docs.vapi.ai/support)
To open a formal support ticket with Vapi, simply email your issue details (including call IDs, error logs, and a description of the problem) to support@vapi.ai. This is the primary method for submitting support requests. For real-time help, you can also join the [Vapi Discord community](https://discord.com/invite/pUFNcf2WmH) and post in the #support channel. Example:
Copy code
To: support@vapi.ai
Subject: Tool Call Validation Issue - appointment_creation_tool

[Describe your issue, include call IDs, error logs, and steps to reproduce.]
Source: - [Vapi Support Documentation](https://docs.vapi.ai/support)
To open a formal support ticket with Vapi, simply email your issue details (including call IDs, logs, and a description of the problem) to support@vapi.ai. This is the official channel for technical support and unresolved issues. For fastest resolution, include all relevant information in your message. Reference: [Vapi Support Options](https://docs.vapi.ai/support) Source: - [Vapi Support Options](https://docs.vapi.ai/support)
To open a formal support ticket with Vapi, simply email your issue details (including call IDs, logs, and a description of the problem) to support@vapi.ai. This is the official channel for technical support and unresolved issues. For fastest resolution, include all relevant information in your message. Reference: [Vapi Support Options](https://docs.vapi.ai/support) Source: - [Vapi Support Options](https://docs.vapi.ai/support)
r
It's not nested, and would you allow nested parameters when you don't support that?
v
Based on the documentation, **Vapi custom tool configurations are expected to use a flat (non-nested) parameter structure**—all required fields should be listed directly under 
properties
, and there are no examples or instructions for using nested parameters. While this strongly suggests that nested parameters are not supported, there is no explicit statement confirming this or describing the system's behavior if nesting is attempted. Could you clarify if you have a specific use case that requires nested parameters, or are you asking to confirm whether nesting is officially unsupported due to the issues you've observed? For reference, see the [Custom Tools Documentation](https://docs.vapi.ai/tools/custom-tools). Source: - [Custom Tools Documentation](https://docs.vapi.ai/tools/custom-tools)
Based on the documentation, **Vapi custom tool configurations are expected to use a flat (non-nested) parameter structure**—all required fields should be listed directly under 
properties
, and there are no examples or instructions for using nested parameters. While this strongly suggests that nested parameters are not supported, there is no explicit statement confirming this or describing the system's behavior if nesting is attempted. Could you clarify if you have a specific use case that requires nested parameters, or are you asking to confirm whether nesting is officially unsupported due to the issues you've observed? For reference, see the [Custom Tools Documentation](https://docs.vapi.ai/tools/custom-tools). Source: - [Custom Tools Documentation](https://docs.vapi.ai/tools/custom-tools)
Vapi does not support nested parameters in custom tool configurations. All required fields must be listed at the top level of the 
properties
object, as shown in the official examples. Attempting to use nested parameters is not documented as supported and may result in unexpected behavior. Would you like more details on how Vapi handles invalid (e.g., nested) tool configurations at runtime, or are you asking about possible future support for nested parameters? [Custom Tools Documentation](https://docs.vapi.ai/tools/custom-tools) Source: - [Custom Tools Documentation](https://docs.vapi.ai/tools/custom-tools)
Vapi does not support nested parameters in custom tool configurations. All required fields must be listed at the top level of the 
properties
object, as shown in the official examples. Attempting to use nested parameters is not documented as supported and may result in unexpected behavior. Would you like more details on how Vapi handles invalid (e.g., nested) tool configurations at runtime, or are you asking about possible future support for nested parameters? [Custom Tools Documentation](https://docs.vapi.ai/tools/custom-tools) Source: - [Custom Tools Documentation](https://docs.vapi.ai/tools/custom-tools)
Vapi does not support nested parameters in custom tool schemas. All required parameters must be defined as top-level properties within the 
parameters
object—nesting (objects within objects) is not allowed. If you attempt to use nested parameters, the platform's behavior is not documented, so it is best to avoid nesting entirely. Reference: [Custom Tools Documentation – "no nesting"](https://docs.vapi.ai/tools/custom-tools) Source: - [Custom Tools Documentation](https://docs.vapi.ai/tools/custom-tools)
p
Hey RPV, you have to increase your assistant max tokens limit from 100 to 500. This way, the parameters won't get truncated, and you'll be able to use them. Try 2-3 calls, and let me know how it goes for you.
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