reply_email

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It adds useful context by stating that it handles In-Reply-To, References, and quoted text formatting, which are meaningful behaviors not visible in the schema. However, it does not state whether the reply is sent immediately or created as a draft, how quoted text is combined with bodyText, or what side effects occur.

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 two short sentences with no filler. The main purpose is front-loaded, and the second sentence adds relevant email-specific behavior without wasting words.

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 description is sufficient to understand the basic operation: reply to an email with a body and optional HTML. However, given the absence of annotations and output schema, it leaves important gaps around send-vs-draft behavior, how quoted content is formatted relative to bodyText, and what the result or failure mode looks like.

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 100%, so the schema already documents all five parameters, including defaults. The description does not add parameter-specific meaning beyond the general mention of quoted text formatting, so the baseline score 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 states a specific verb and resource: 'Reply to an existing email.' It also names concrete email behaviors (In-Reply-To, References, quoted text formatting) that clarify what the tool does. It does not explicitly differentiate from siblings like send_email or forward_email, but the reply-focused wording makes the core purpose clear.

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 the intended use: replying to an existing email rather than composing a new one or forwarding. However, it provides no explicit condition for when to choose this tool over send_email, forward_email, or create_draft, and gives no exclusions or prerequisites.

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