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

With no annotations, the description carries the burden and does disclose the crucial traits: it is a dry run and "Nothing changes", so an agent knows it is non-mutating, and it reports a count of emails that would be scheduled into working hours. It omits auth requirements and error conditions (e.g., no prepared emails ready), keeping it below top marks.

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?

Three short sentences, all load-bearing, with the dry-run nature front-loaded before the output description and the sequencing instruction. No filler.

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 preview with no output schema, the description supplies everything needed: that it is non-mutating, what it returns (a count of emails schedulable within working hours), and where it fits relative to schedule_campaign_delivery.

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 and schema coverage is 100%, with the schema already documenting that id is the campaign UUID sourced from list_campaigns. The description adds nothing about the id beyond that, 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?

Specific verb (dry-run preview) plus resource (scheduling of ready prepared emails into campaign working hours) plus the key output (a count). It is unmistakably distinct from its sibling schedule_campaign_delivery, which the description names.

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?

"Call before schedule_campaign_delivery" gives an explicit sequencing rule and names the alternative tool. It does not state conditions under which the preview should be skipped (e.g., already-scheduled campaigns), so it falls short of full when/when-not coverage.

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