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

With readOnlyHint=false and openWorldHint=true already declared, the description still adds substantial behavior: nothing is delivered to contacts, variables are filled from a real contact, reply steps inherit their thread's subject, and test subjects get a 'test' suffix. That is exactly the extra context annotations cannot convey.

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?

Long but dense and front-loaded — the core action, the non-delivery guarantee, and the step/sender/variable conventions come in a deliberate order with no filler sentences. Some clauses (subject suffix) are minor detail, but none are pure padding.

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 adequately covers what happens (mail arrives in the user's inbox, subject suffixed 'test') plus the operational constraints. Nothing an agent needs to invoke this correctly is missing.

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%, so the baseline is 3, but the description adds meaning beyond the schema: 'from one of the campaign's inboxes' clarifies the sender_id default, the {{variables}} filling explains contact_id in operational terms, and the step/step-omission convention ties to get_campaign_review.

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?

Opens with a precise verb+resource+scope: sends test emails of a campaign's email steps to the user's own inbox before launch. It distinguishes itself from preview_campaign and get_campaign_review (which it references for step numbering) and explicitly rules out sending to contacts.

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?

States the when ('before launch'), the fallback behavior (omit step to send every email step), the narrow condition for using `to` ('only to send to another address the user names'), and names get_campaign_review as the source of step numbering. An agent can pick this over siblings without inference.

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