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

With annotations covering safety (readOnly, idempotent, non-destructive), the description still adds the response shape (email, name, lists, time) and the pagination bound, which the agent would otherwise have to discover. It omits sort order and whether links are broken out individually, which is what get_click_map might cover.

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, front-loaded with what is returned and followed by paging and optional filters. No redundant or filler wording.

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 five-parameter read tool with a fully described schema and no output schema, the description supplies the returned column set and paging behavior, which is what an agent needs. It could say more about ordering or per-link breakdown but is adequate overall.

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%, so the schema already documents page, limit, date_from and date_to including defaults and timezone. The description only restates limit 1-100 and optional dates, adding no new meaning, so the baseline 3 applies.

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?

States a specific verb and resource ('List the contacts who clicked a link in a campaign') and names the returned fields, which distinguishes it from get_campaign_opens and get_campaign_unsubscribes by the click event. It doesn't explicitly name a sibling, so an agent must infer the distinction.

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?

Usage is implied by the click-event scope, and the date_from/date_to note hints at narrowing by time, but there is no explicit when-to-use or when-not-to-use guidance versus related reporting tools like get_click_map.

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