reply_email

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

With no annotations, the description carries the disclosure burden; it does reveal the important threading behavior and its conversational effect. However, it does not state whether the reply is sent immediately, what side effects occur (e.g., a sent copy), or what permissions are required.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

A single sentence with no filler; the threading detail is relevant and front-loaded. Every clause contributes something the agent needs to know.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

The core purpose is complete and an output schema is present, so return-value explanation is not required. Yet optional parameters with defaults (quote, reply_all, account, mailbox) are not explained and there are no annotations, leaving real gaps for selecting and invoking correctly.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 0%, and the description adds no parameter-level meaning. It does not clarify the role of uid/body, the quote default, reply_all behavior, or account/mailbox selection, leaving the agent to infer these from names and defaults.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description names the exact operation ('Reply to an email') and adds the distinctive threading requirement (In-Reply-To/References) and the ProtonMail context, making it easy to distinguish from sibling tools like send_email and forward_email.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

It clearly implies the right context—replying to an existing email while preserving the thread—but it never explicitly names alternatives or states when not to use it (e.g., for a new message use send_email).

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.