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

With no annotations provided, the description carries the behavioral burden and does disclose the critical trait: this is a dry-run and 'Nothing is sent', so the agent knows it is non-mutating. It also describes the return value ('how many prepared emails would be sent') despite having no output schema. Permissions and rate limits are not mentioned, but for a read-only preview that is a minor gap.

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?

The description is a single, front-loaded sentence that immediately signals 'Dry-run' and then clarifies the outcome. Every word earns its place with no redundancy.

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?

Given no annotations, no output schema, and fully documented parameters, the description is nearly complete: it explains the purpose, the non-mutating nature, and the essence of the return value. It could have added a note about what 'prepared emails' means or when to use this vs the actual send tool, but the core information is present.

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 both parameters (id, limit) are fully documented in the schema. The description adds the concept of 'prepared emails' and 'outside the schedule' but does not provide additional syntax or format details beyond what the schema already conveys.

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+resource: a dry-run of sending prepared campaign emails now, with the clarifying detail that nothing is sent. It implicitly distinguishes itself from the sibling send_campaign_emails_now by being a preview-only operation, making the intent unmistakable.

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?

The phrase 'Dry-run' and 'Nothing is sent' imply this is a safe pre-check before an actual send, but the description does not explicitly name the alternative tool (send_campaign_emails_now) or state when not to use this preview. Usage is implied rather than spelled out.

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