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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is covered. The description adds useful context beyond that: the email is tuned by overdue stage (1-6) and relationship intent, the email field is required to attribute the request, and a side effect is disclosed (occasional updates, never spam). This is richer than the annotations alone.

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; the first front-loads what the tool produces, the second covers the requirement and side effect. No wasted words, though the side-effect disclosure adds a bit of length.

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 generation tool with a rich 13-param schema and no output schema, the description covers the core behavior, tuning dimensions, and the required email parameter plus a disclosure about usage. It omits details like output format (which the API likely defines implicitly) but is largely complete for correct invocation.

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 13 parameters, including the stage enum values, relationship enum, and usage notes for daysOverdue. The description adds only a high-level mention of the stage/relationship axes and the email's role, not new parameter syntax or constraints. Baseline 3 is appropriate when the schema does the heavy lifting.

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+resource ('Generate a ready-to-send accounts receivable follow-up email for an overdue or upcoming invoice') and adds the tuning axis. Clearly distinct from siblings like parse_invoice or calculate_invoice_due_date, which do not produce email content.

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 when to use it (overdue or upcoming invoice) and mentions the stage/relationship tuning, but provides no explicit when-not-to-use or guidance on choosing among the sibling tools. Usage context is present but thin.

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