How to create a tool that has no inputs?

[augustocdias]

I'm trying to create a tool to let the LLM read my emails:

local handlers = require('ai.cc.utils')

local mail_script = [[
tell application "Mail"
	set unreadMsgs to (every message of inbox whose read status is false)
end tell

set outText to ""
repeat with m in unreadMsgs
	tell application "Mail"
		set outText to outText & "-----" & linefeed
		set outText to outText & "Subject: " & (subject of m) & linefeed
		set outText to outText & "From: " & (sender of m) & linefeed
		set outText to outText & "Date: " & ((date received of m) as text) & linefeed
		set outText to outText & "Message-ID: " & (message id of m) & linefeed & linefeed
		set outText to outText & (content of m) & linefeed & linefeed
	end tell
end repeat
return outText
]]

return {
    name = 'apple_mail',
    cmds = {
        function(_, _, _, output_handler)
            if vim.fn.has('mac') == 0 then
                return output_handler({ status = 'error', data = 'AppleScript is only available on macOS' })
            end

            local cmd = { 'osascript', '-e', mail_script }

            vim.system(cmd, function(result)
                vim.schedule(function()
                    if result.code ~= 0 then
                        output_handler({
                            status = 'error',
                            data = 'AppleScript failed with exit code '
                                .. result.code
                                .. ': '
                                .. (result.stderr or 'unknown error'),
                        })
                    else
                        output_handler({ status = 'success', data = result.stdout or '' })
                    end
                end)
            end)
        end,
    },
    schema = {
        type = 'function',
        ['function'] = {
            name = 'apple_mail',
            description = 'Fetch unread emails from Apple Mail',
            strict = 'true',
            parameters = {},
        },
    },
    system_prompt = [[Fetch unread emails from Apple Mail application on macOS. This is a specialized read-only tool for retrieving email information.

**What it returns**:
For each unread email in the inbox, you'll get:
- Subject line
- Sender email address
- Date received
- Message-ID (unique identifier)
- Full email content/body

**Use Cases**:
- Check for new emails without opening Mail.app
- Get email content for processing or analysis
- Monitor inbox for specific messages
- Extract information from recent emails
- Build email summaries or reports

This tool is read-only and does not modify any emails or mark them as read. It simply queries the Mail application for unread messages in the inbox. Only works on macOS systems with Mail.app configured.]],
    output = {
        error = handlers.default_error_handler,
        success = handlers.default_success_handler,
    },
}

I'm getting errors when I execute it and I guess its because I don't have any input parameters:

[ERROR] 2025-10-07 09:24:29
Error 400: {"type":"error","error":{"type":"invalid_request_error","message":"tools.3.custom.input_schema: Input does not match the expected shape."},"request_id":"req_011CTsSPM4ScjbLXm41TQroF"}
[ERROR] 2025-10-07 09:24:29
[chat::_submit_http] Error: {
  body = '{"type":"error","error":{"type":"invalid_request_error","message":"tools.3.custom.input_schema: Input does not match the expected shape."},"request_id":"req_011CTsSPM4ScjbLXm41TQroF"}',
  exit = 0,
  headers = { "date: Tue, 07 Oct 2025 07:24:29 GMT", "content-type: application/json", "content-length: 183", "cf-ray: 98aba8bde9825315-TXL", "x-should-retry: false", "request-id: req_011CTsSPM4ScjbLXm41TQroF", "strict-transport-security: max-age=31536000; includeSubDomains; preload", "anthropic-organization-id: a5bc8914-7ddb-4689-8414-fbb4c9e7425a", "x-envoy-upstream-service-time: 11", "via: 1.1 google", "cf-cache-status: DYNAMIC", "x-robots-tag: none", "server: cloudflare" },
  status = 400
}

is there a way to define a tool without any input?

[olimorris]

This is the LLM throwing an error - not CodeCompanion. You'll need to conform to their tool spec which is likely to be OpenAI's

[augustocdias]

I understand. Do you know if it is possible to add a tool without any input defined?

[olimorris]

I don't think I've ever tried. I don't think it's a requirement of CodeCompanion however

[augustocdias]

Yeah... I figured but passing an empty property list causes this error. I guess I'll have to create a placeholder parameter to make the API happy...

[olimorris]

Which LLM are you using?

[augustocdias]

Claude