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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint, so safety is covered. The description adds meaningful behavior beyond those annotations: results are grouped by destination URL and only links from trackClicks-enabled sends are counted. It does not discuss response shape or pagination, but the core filtering behavior is transparent.

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 sentences with no filler. The first sentence front-loads the resource, grouping behavior, and accepted identifiers; the second adds the key tracking precondition. Every clause earns its place.

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 read-only two-parameter tool with fully described schema properties and no output schema, the description provides the required parameter relationship, the grouping concept, and the filtering caveat. It does not spell out the exact response fields, but 'click counts grouped by destination URL' gives enough shape for an agent to invoke and interpret the result.

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 coverage is 100%, so the baseline is 3, but the description adds real semantics: at least one of sendId/campaignId is required, campaignId totals across many sends, and only tracked-link emails contribute. These details are not encoded in the schema's property constraints and meaningfully shape invocation.

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 uses a specific verb and resource: it returns email link click counts grouped by destination URL, and it identifies the query scope (sendId, campaignId, or both). This clearly separates it from sibling read tools like get_send_status and get_usage.

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 description states what identifiers the tool operates on and that at least one is required, and it gives an important precondition (trackClicks: true). However, it never explicitly contrasts this with alternatives such as get_send_status or get_usage, so an agent must infer when this tool is the right choice.

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