reply-to-message

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

With no annotations provided, the description fully discloses critical behavior: sending sends real email immediately and cannot be unsent, requiring explicit user confirmation. It also mentions the draft-saving option and threading preservation.

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 concise (6 sentences) and well-structured with clear sections: action, usage, parameters, returns, exclusions, safety. Every sentence adds value.

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 complexity of email actions and many sibling tools, the description is complete: it covers purpose, when to use, when not to use, parameter roles, safety, and return value. No gaps.

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 descriptions cover 50% of parameters (send, replyAll have descriptions). The description adds meaning for id and body by context (replying to an existing message) and clarifies the effect of send and replyAll beyond their boolean labels.

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's purpose: 'replying to an existing message by id, preserving its threading headers.' It specifies key options (replyAll, send) and distinguishes from sibling tools like send-email, create-draft, and forward-message.

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?

Explicit 'Use when' and 'Do not use when' sections provide clear usage boundaries, including naming alternative tools for other scenarios (send-email, create-draft, forward-message).

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