The agent fills in the form fields, but the user must review and click Search to submit. Only toolname and tooldescription are required.

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Adding toolautosubmit lets the agent fill and submit the form automatically, no manual click required.

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With a submit event listener you can intercept agent submissions, run your own logic, and return a custom value to the agent via event.respondWith().

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Declarative WebMCP API Reference

Attribute Applies to Description
Form attributes
toolname <form> Registers the form as a WebMCP tool. Must be unique on the page. Letters, digits, hyphens, underscores, and dots only.
tooltitle <form> Optional friendly display name shown in UIs. The agent uses toolname for invocation.
tooldescription <form> Human-readable description of what the tool does. Helps the AI agent decide when and how to use this tool.
toolautosubmit <form> When present, the form is submitted automatically after the agent fills it in. Without this, the user must submit manually.
Input attributes
toolparamdescription <input>, <select>, <textarea> Describes the parameter so the agent knows what value to provide. For example: "Event date in YYYY-MM-DD format".
SubmitEvent properties
event.agentInvoked SubmitEvent Boolean. true when the form submission was triggered by an AI agent, false when submitted by the user.
event.respondWith(promise) SubmitEvent Pass a Promise that resolves to the tool's return value. This lets you customize what the AI agent receives after form submission.