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

Annotations already declare readOnlyHint=false, idempotentHint=true, and destructiveHint=false. The description adds that this sends a connection test and confirms authentication/send capability, which is useful, but it does not reveal details like whether a test email is actually sent, possible failure modes, or any external side effects beyond the test itself.

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 short sentences, no filler, and the main action is front-loaded. Every word contributes either to explaining what the tool does or when to use it.

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 single-parameter tool with no output schema and no nested objects, the description adequately covers purpose, usage timing, and expected outcome. It does not specify the exact return value or result format, but for a connection test this is a minor gap.

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 100%, and the only parameter, mailbox_id, is described as 'Mailbox id from list_mailboxes.' The description does not need to add parameter details; the schema fully documents it.

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 names a specific action ('Send Getlead's connection test') and a specific resource ('one mailbox'), and it states the intended outcome ('confirm it can authenticate and send'). This clearly differentiates test_mailbox from sibling tools like check_deliverability or verify_email, which target email addresses rather than mailbox credentials.

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 gives explicit context for when to use the tool: 'Use it before launching a campaign from a mailbox that has never sent.' It does not explicitly name alternatives or when not to use it, but the timing guidance is clear and sufficient for this simple tool.

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