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

With no annotations, the description carries the full behavioral burden and does well: it declares 'Nothing is sent' and lists what the preview exposes (recipient, subject, exact text). It does not cover prerequisites (e.g. the email must be an existing reply thread) or validation/error behavior, leaving a minor gap.

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?

Two sentences, zero waste, with the safety fact ('Nothing is sent') and the sequencing instruction both front-loaded and easy to scan.

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?

No output schema exists, and the description compensates by naming the returned fields (recipient, subject, exact text). For a 2-parameter no-mutation tool this is nearly complete, though the email_id parameter's meaning remains under-specified.

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 only 50%; email_id is undocumented in the schema. The description implies email_id is the lead's reply being responded to and body is the 'exact text', but adds no format, ID-type, or HTML details beyond the schema's own 'HTML allowed' note.

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?

States a specific verb and resource: a dry-run preview of replying to a lead's email reply. It explicitly contrasts with the real action (reply_to_campaign_email), so the agent can distinguish it from the write sibling even among many preview_* tools.

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?

Names the alternative write tool (reply_to_campaign_email) and the condition for choosing this one: call it first and show the text to the user. The sequencing requirement is explicit and leaves nothing to inference.

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