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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false, and openWorldHint=false, so the safety and repeat-safety profile is fully covered. The description adds real value by disclosing the 30-day lookback and the per-day breakdown, but says nothing about whether results are cached, per-segment, or how missing days are handled.

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?

One tight sentence with no filler, front-loading the scope (last 30 days by day) ahead of the metric list. Slightly clipped grammar ('A message's last 30 days by day') costs a point but wastes nothing.

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?

With no output schema, the description carries the burden of explaining return values and does so by enumerating the six metric dimensions at daily granularity. It is nearly complete for a single-parameter read-only report; only the exact response shape (e.g., array of daily objects) is left unstated.

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% and the single required parameter (messageId) is documented in the schema as originating from list_proactive_messages. The description adds no further parameter guidance, which is the expected baseline 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?

The description names the resource (a proactive message) and its exact output dimensions (shown, seen, clicked, replied, dismissed, goal conversions) over a defined 30-day window, which clearly separates it from get_proactive_message and list_proactive_messages. There is no explicit verb phrase, but the metrics inventory makes the purpose unmistakable.

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 only usage signal is the implicit 30-day window; there is no statement of when to reach for this report versus get_proactive_message, list_proactive_messages, or the generic report_summary. An agent must infer the analytics use case on its own.

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