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

Annotations already declare readOnlyHint=true, idempotentHint=true and destructiveHint=false, so 'Saves nothing' largely restates structured data rather than adding to it. The description does not say what happens if the campaign is not paused, whether the count includes queued-but-unapproved messages, or how the count is composed.

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 short sentences, the operation and its precondition front-loaded, followed by the no-write reassurance. Nothing is padded or redundant.

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 one-parameter read tool with rich annotations and no output schema, the description is close to sufficient but leaves the return shape ambiguous — it 'counts' messages, yet an agent cannot tell whether the result is a bare number, a breakdown by step, or includes unapproved messages. The unspecified id parameter meaning is the other gap.

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 0% for a single nested parameter that requires a UUID 'id', and the description never says this parameter identifies the campaign. The reader must infer the parameter's meaning from 'a paused campaign', which is the only hint provided.

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 ('Counts the approved messages') plus the triggering condition ('when a paused campaign resumes'), which is far more informative than the title alone. It does not, however, distinguish itself from adjacent tools such as previewCampaign or getSendForecast, so an agent cannot rule out overlap from the text alone.

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?

'when a paused campaign resumes' implies the context in which this is useful, and 'Saves nothing' hints it is safe to call before a real resume. There is no explicit when-not guidance, no named alternative for forecasting totals, and no statement about prerequisites such as the campaign actually being paused.

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