Reply to Email

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

Annotations already flag destructiveHint=true and readOnlyHint=false, so the description adds valuable context: it 'sends immediately' and 'quoting the original,' which warns the user that the action is irreversible and affects the email thread. This goes beyond the structured annotations without contradicting them.

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?

The description is compact and front-loaded: two sentences that convey the core purpose, the quoting behavior, and the immediate-send consequence. Every word earns its place with no filler or repetition.

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?

Given the output schema, full annotation coverage, and complete parameter descriptions, the description sufficiently covers the tool's primary behavior. It could mention that replying includes the original text or the immediate-send consequence, which it does. Minor gaps like potential attachments or undo options are not necessary given the structured metadata.

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?

The input schema covers 100% of parameters with descriptions, so the description does not need to repeat them. However, it adds no new parameter-level context beyond what the schema already provides, such as the significance of body_type or reply_all. The baseline of 3 is appropriate.

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 clearly states the action ('Reply to an email'), the resource (email), and key behavior (quoting the original, sending immediately). This distinguishes it from sibling tools like send_email and forward_email, which send new emails or forward existing ones.

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?

The description implies usage (when you want to reply to an existing email) but does not explicitly contrast with alternatives like send_email or forward_email, nor provide exclusions. There is no 'when not to use' guidance, so it falls at the implied-usage level.

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