Reply to Email

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

Annotations indicate no destructive behavior (destructiveHint=false), and the description adds context about pre-filling fields. However, it does not disclose potential side effects like marking the original email as replied or any permissions needed. With annotations covering basic safety, the description adds moderate value.

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 extremely concise: two sentences that front-load the purpose and immediately provide actionable guidance on replyAll. Every sentence serves a clear purpose with no waste.

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?

With an output schema present, the description need not explain return values. It covers the core action and the primary variation (replyAll). It lacks details on error handling, prerequisites (e.g., email must exist), or behavior of isHtml, but these are minor gaps for a mutation tool with 6 parameters.

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 coverage is 83%, so the schema already documents most parameters well. The description only adds meaning for the 'replyAll' parameter by explaining its usage. Other parameters like 'folder' and 'account_id' are not elaborated, but baseline 3 is appropriate given high schema coverage.

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 tool sends a reply to an existing email, specifies that it fetches the original to pre-fill fields, and distinguishes between reply and replyAll. This differentiates it from siblings 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?

The description provides explicit guidance on using replyAll for including original CC recipients, implying the default is to reply only to the sender. It lacks explicit when-not-to-use scenarios or alternatives like 'forward_email', but the context is clear enough.

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