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

Annotations already declare the write/idempotency/safety profile (readOnly=false, idempotent=false, destructive=false), so the description only needs to add context. It does: 'each matching event sends one email to the contact' conveys the runtime effect of the created resource, which is not derivable from annotations or schema. It omits auth requirements and duplicate-eventName behavior, keeping it below 5.

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, no filler, and the core purpose is front-loaded before the behavioral detail. Every sentence earns its place.

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 7-parameter create tool with strong annotation coverage and 86% schema coverage, the description covers what the tool does and its runtime effect. It does not indicate what is returned (e.g., the created action's id) — no output schema exists to cover this — which is the main remaining 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 description coverage is 86%, so the schema already documents nearly all parameters and the baseline is 3. The description echoes the eventName-to-templateSlug mapping but adds no meaning for delaySeconds, sendOnce, enabled, or apiKey beyond what the schema states. No compensation for the small remaining gap.

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 gives a specific verb (create) plus the resource (Action) and then defines what an Action is in domain terms — a mapping from event name to transactional template. That definition is genuinely useful because 'Action' is jargon that could otherwise be confused with create_campaign or send_email. It stops short of naming a sibling to distinguish itself from, so it lands at 4 rather than 5.

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?

There is no guidance on when to use this versus create_campaign, create_webhook, or send_event, and no prerequisites stated (e.g., that the referenced templateSlug must already exist, or that events are fired via send_event). The trigger semantics are described, but nothing tells the agent when this tool is the right choice.

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