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

Annotations already declare readOnlyHint/idempotentHint/destructiveHint=false, so the safety profile is covered. The description adds non-obvious behavioral semantics beyond that: sendStatus.isWithinSchedule is computed from the schedule and start/end dates for any status, and a draft or paused campaign still does not send, plus the next-window timing. It does not cover auth/rate limits or pagination, but for a read lookup this is unusually substantive.

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?

Front-loaded with the payload summary, and every clause carries information (return contents, cross-tool field mapping, schedule semantics). The second half is a single dense sentence with nested parentheticals, which is slightly heavy but not padded.

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?

There is no output schema, so the description must convey the return shape — and it does, enumerating the major payload sections and one key nested field path. Combined with the schedule/send-window semantics, an agent has everything needed to call and interpret this tool.

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?

Only one parameter (id, UUID) and schema description coverage is 100%, so the schema fully documents it. The description adds no format or lookup guidance for the id beyond what the schema states, 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+resource ('One campaign') and enumerates exactly what is returned: schedule, settings, metrics, attached mailboxes, and the sequence with steps/variants. It is immediately distinguishable from list_campaigns (plural collection) and from get_campaign_analytics.

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?

Gives a concrete cross-tool usage cue by naming the field to consume ('sequence[].variants[].id is the variantId for send_test_email'), which tells the agent when to reach for this tool. It stops short of explicit alternatives or exclusions (e.g. use list_campaigns to find ids, use analytics for time-series metrics).

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