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

Annotations already declare readOnly=true, idempotent=true, non-destructive and open-world, so the safety profile is covered. The description adds real value beyond that: pagination constraints (limit 1-100), the optionality of date_from/date_to, and the meaning of the 'reason' values ('Abuse when they reported spam'). It does not discuss ordering or what happens with an invalid campaign_id, which keeps it short of a 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 dense sentences with the purpose front-loaded and no filler. The telegraphic style ('Paged (limit 1-100); optional date_from/date_to') is efficient, though the semicolon fragment reads slightly like schema restatement rather than prose.

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 correctly compensates by enumerating the returned columns and explaining the reason values, and it covers paging and date filtering. Minor gaps remain: result ordering, page-size default (only in the schema), and behavior when a campaign has no unsubscribes.

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 campaign_id, page, limit, date_from and date_to are already documented, and the description only echoes the limit range and the date filters. Its only genuine semantic addition is clarifying the reason field's values, which concerns the response rather than the inputs. Baseline 3 applies 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 states a specific verb and resource ('List the contacts who unsubscribed from a campaign') and even enumerates the returned fields (email, name, lists, time, reason). It is clearly distinct from the parallel analytics siblings such as get_campaign_opens and get_campaign_clicks, though it never names an alternative explicitly.

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 name and the returned-field list: use this to inspect who opted out of a given campaign. There is no explicit when-to-use / when-not-to-use statement, no mention of prerequisites, and no routing to related tools (e.g., list_suppressions or get_campaign) for account-wide opt-outs.

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