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

Annotations already declare readOnlyHint, idempotentHint, non-destructive and closed-world, so the safety profile is covered. The description adds meaningful content beyond that: it enumerates the returned payload (trigger, start and sending settings, emails with steps and A/B variants, enabled/state flags, and entered/in-progress/replied/positive counters), which substitutes for the absent output schema. It does not mention pagination or ordering, which keeps it off 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?

A single dense sentence, front-loaded with the resource and then the return contents; every clause (trigger, settings, emails, enabled state, counters) conveys information an agent would otherwise have to discover by calling. It is long but not padded, though splitting the return-field list from the definition would improve scannability.

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 single-parameter, read-only list tool with no output schema, the description does the heavy lifting by describing return structure, which is exactly what an agent needs. Gaps are minor: result ordering, pagination, and behavior for an unknown or empty campaign are 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 campaignId is documented as a UUID, so the schema carries the parameter meaning. The description only implies scoping via 'of a campaign' and adds no format or constraint detail beyond the schema. 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?

The description names the resource (subsequences of a campaign) and defines it precisely as 'follow-up flows that start on a lead status, a reply, an open, a click or a finished main sequence,' which lets an agent distinguish this from the campaign-level siblings get_campaign and list_campaigns. It reads as a noun phrase rather than an explicit verb, so the 'list' action comes mostly from the name and title, but the scope is unambiguous.

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: nothing says whether to call this instead of get_campaign (which may also surface subsequence data) or before enroll_in_subsequence / update_subsequence. No prerequisites, no empty-state behavior, and no indication of what happens if the campaign has no subsequences.

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