reply_to_email

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

With no annotations provided, the description carries full burden. It details behaviors: sending vs. draft via 'send' and 'mode' parameters, HTML support with fallback, attachments, CC/BCC, and return of confirmation message. It could note that the original email is not modified, but overall is transparent.

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 structured as a list of parameters with clear explanations, which is necessary given no schema descriptions. It is somewhat long (16 lines) but front-loads the purpose and uses consistent formatting. Slightly verbose but efficient.

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 10 parameters, no annotations, and presence of an output schema (confirmed by context), the description covers all behavioral aspects, parameter semantics, and return type. It is fully adequate for an agent to use this tool 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%, but the description explains every parameter in depth, including defaults, overrides (mode vs. send), formatting (body_html with fallback), and multiple recipients (CC/BCC as comma-separated). This fully compensates for the schema's lack of descriptions.

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: 'Reply to an email matching a subject keyword.' It uses a specific verb (reply) and resource (email) with a filtering mechanism, distinguishing it from siblings like compose_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 implies usage (when you want to reply to an existing email via subject keyword) but lacks explicit guidance on when to use this vs. alternatives like forward_email or compose_email. No exclusions or when-not-to-use advice is provided.

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