microsoft/semantic-kernel · error · ArgumentException

The option keys 'name' and 'type' are required for a paramet

Error message

The option keys 'name' and 'type' are required for a parameter.

What it means

Thrown while serializing function/tool parameters from a loosely-typed dictionary. Each parameter dictionary must contain a non-empty 'name' string and a non-empty 'type' string; these become the JSON schema property name and its type. If either is missing or empty the method cannot build a valid OpenAI function parameter spec, so it throws ArgumentException. 'description' and 'required' are optional.

Source

Thrown at dotnet/src/Agents/AzureAI/Extensions/AgentToolDefinitionExtensions.cs:46

        return parameters is not null ? CreateParameterSpec(parameters) : s_noParams;
    }

    internal static BinaryData CreateParameterSpec(List<object> parameters)
    {
        JsonSchemaFunctionParameters parameterSpec = new();
        foreach (var parameter in parameters)
        {
            var parameterProps = parameter as Dictionary<object, object>;
            if (parameterProps is not null)
            {
                bool isRequired = parameterProps.TryGetValue("required", out var requiredValue) && requiredValue is string requiredString && requiredString.Equals("true", StringComparison.OrdinalIgnoreCase);
                string? name = parameterProps.TryGetValue("name", out var nameValue) && nameValue is string nameString ? nameString : null;
                string? type = parameterProps.TryGetValue("type", out var typeValue) && typeValue is string typeString ? typeString : null;
                string? description = parameterProps.TryGetValue("description", out var descriptionValue) && descriptionValue is string descriptionString ? descriptionString : string.Empty;

                if (string.IsNullOrEmpty(name) || string.IsNullOrEmpty(type))
                {
                    throw new ArgumentException("The option keys 'name' and 'type' are required for a parameter.");
                }

                if (isRequired)
                {
                    parameterSpec.Required.Add(name!);
                }
                parameterSpec.Properties.Add(name!, KernelJsonSchema.Parse($"{{ \"type\": \"{type}\", \"description\": \"{description}\" }}"));
            }
        }

        return BinaryData.FromObjectAsJson(parameterSpec);
    }

    internal static FileSearchToolDefinitionDetails GetFileSearchToolDefinitionDetails(this AgentToolDefinition agentToolDefinition)
    {
        var details = new FileSearchToolDefinitionDetails();
        var maxNumResults = agentToolDefinition.GetOption<int?>("max_num_results");
        if (maxNumResults is not null and > 0)

View on GitHub (pinned to c028a0c7dc)

Solutions

1. Ensure every parameter object has 'name' (string) and 'type' (string, e.g. "string", "integer", "boolean", "object", "array").
2. Make sure the values are JSON strings, not numbers/booleans.
3. Optionally add 'description' and 'required': "true".

Example fix

// before
parameters:
  - name: query
    # type missing -> throws 162

// after
parameters:
  - name: query
    type: string
    description: The search query

foreach (var p in parameters)
{
    if (p is not Dictionary<object, object> d) continue;
    bool hasName = d.TryGetValue("name", out var n) && n is string s1 && !string.IsNullOrEmpty(s1);
    bool hasType = d.TryGetValue("type", out var ty) && ty is string s2 && !string.IsNullOrEmpty(s2);
    if (!hasName || !hasType) throw new ArgumentException("Each parameter needs non-empty 'name' and 'type' strings.");
}

static bool IsValidParameter(Dictionary<object, object> p) =>
    p.TryGetValue("name", out var n) && n is string sn && !string.IsNullOrEmpty(sn)
    && p.TryGetValue("type", out var t) && t is string st && !string.IsNullOrEmpty(st);

try { var data = tool.CreateFunctionParameters(parameters); }
catch (ArgumentException ex) when (ex.Message.Contains("'name' and 'type'"))
{ /* surface a friendly validation error to the config author */ }

When it happens

Trigger: A tool definition's 'parameters' list contains a dictionary entry where TryGetValue('name') is not a string (or absent) or TryGetValue('type') is not a string (or absent). Note the code only accepts string-typed values, so a non-string value also reads as null and triggers this.

Common situations: Malformed agent definition parameter list. A numeric or boolean value supplied where a type string is expected. Parameter dict missing the 'type' key.

Related errors

• Azure AI Search tool definition must have both 'index_connec
• The option keys 'asset_identifiers' and 'asset_type' are req
• The option keys 'store_name' and 'data_sources' are required
• The option key '{bindingType}.storage_service_endpoint' is r
• The option key '{bindingType}.queue_name' is required.

AI-assisted analysis of microsoft/semantic-kernel@c028a0c7dc (2026-08-13). Data as JSON: /api/errors/f159d000f89dd65c. Report an issue: GitHub.