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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false, and openWorld=false, so the safety profile is covered. The description usefully discloses the breadth of returned data (anonymous viewers included, live 'watching now' status), but says nothing about the filter's behavioral effect, result size, or pagination.

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 front-loaded sentence that leads with the core resource ('Everyone who opened one of your links') and then enumerates the useful detail. Efficient, though the comma-segmented clause stack is slightly dense.

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 does the work of explaining what comes back (viewer types, watch amount, live status), which is appropriate for a read-only list tool. The only real omission is any explanation of the filter parameter.

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?

There is a single filter parameter with enum values (watching, engaged, dropped) and 0% schema description coverage, yet the description never mentions it or what the three states mean. The enum names are somewhat self-evident but the description does not compensate for the coverage 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 states a specific resource and scope: everyone who opened one of your links, broken down by recipient, forwarded, and anonymous viewers, plus watch depth and live status. An agent can tell this is a viewer/engagement listing tool, though it never explicitly contrasts itself with siblings like list_links or get_moments.

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 when-to-use guidance, no statement of prerequisites, and no named alternative for filtering or exploring related data. The agent must infer entirely from the name and one enum parameter that this is the viewer-detail view.

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