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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=true, so safety is covered. The description adds the REST endpoint (GET /v1/reports/{campaignId}) and the returned metric set, but says nothing about behavior for unsent campaigns, empty results, or rate limits.

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 compact sentence front-loads the resource and then enumerates the payload metrics, with the endpoint appended as a trailing reference. No filler or repetition.

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?

With no output schema present, the description carries the burden of describing return values, and it does so by listing the metric categories per send. What is missing is only secondary: result shape granularity (e.g., per-send breakdown structure) and error/empty-case behavior.

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?

There is only one parameter and schema description coverage is 100%, so the schema fully documents campaign_id including its pattern and length bounds. The description adds a small amount of meaning via 'per send', implying the id must reference a campaign that has already been sent, but no additional syntax or sourcing guidance.

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?

Names a specific verb+resource ('statistics of a campaign') and enumerates the exact metrics returned (delivered, opens, openers, clicks, clickers, unsubscribers, devices, OS), which clearly separates it from sarbacane_get_campaign (campaign metadata) and sarbacane_list_campaign_recipients. It stops short of explicitly naming those siblings, so differentiation relies on the agent inferring it.

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 'per send' phrasing implies this is for post-send performance analysis, but there is no explicit statement of when to use this versus sarbacane_get_campaign or the recipient-list tools, and no note about the campaign needing to have been sent. Usage is inferable but not stated.

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