preview_email

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

With no annotations, the description carries full burden. It discloses key behaviors: the tool does not send, returns a single-use confirm_token valid for 10 minutes, and that sending must go through the token handoff. It also states the exact output (payload plus token) and design constraint on BCC.

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 short and front-loaded with the main purpose. Each sentence adds critical workflow information without redundancy, achieving high information density in three concise sentences.

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?

For a tool with 10 parameters and no output schema, the description adequately covers the workflow, token expiry, and the necessity of calling send_email. However, it lacks details on validation error behavior and the exact structure of the returned payload, which slightly limits completeness given the schema's absence.

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%, so the description must compensate by explaining parameter meanings, but it only mentions BCC (which is not even a parameter). It does not explain how to, from_email, template_id, template_data, body_html, or other fields are used, leaving the agent without guidance beyond raw schema definitions.

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 function: 'Validate and render an email WITHOUT sending it.' It also distinguishes itself from the sibling send_email by explaining the token-based handoff and the absence of a direct-send path.

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 explicitly explains when to use this tool: it is a prerequisite for sending, as 'Sending requires passing that token to send_email — there is no direct-send path.' It also notes that BCC is not accepted, providing a clear constraint.

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