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

readOnlyHint=true already tells the agent this is a safe read, so the annotation carries the safety profile. The description adds useful context by describing the shape of the payload (one entry per link with URL and click counts), but says nothing about pagination, rate limits, or behavior when the campaign has no links.

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?

One dense sentence states the resource and the return shape, followed by the underlying endpoint — front-loaded and free of filler. Slightly compact; the API path is useful orientation rather than waste.

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, the description usefully tells the agent what the return contains, and the read-only annotation covers safety. For a single-parameter read tool this is close to complete; only pagination/empty-result behavior is unaddressed.

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% for the single required campaign_id parameter, so the schema already documents it. The description's endpoint template (/campaigns/{campaign_id}/reports/links) corroborates the identifier's role but adds no format or sourcing detail beyond the schema, making the baseline 3 appropriate.

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 gives a specific verb and resource ('Get a campaign's per-link click report') and specifies the payload ('the URL and its click counts'), which separates it conceptually from the generic get_campaign_report sibling. It never names that sibling or the other campaign tools, so sibling differentiation is left implicit rather than explicit.

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?

Usage is only implied by the narrow scope of 'per-link click report' — an agent can infer this is the drill-down after a general campaign report, but the description states no when-to-use condition, no prerequisites, and no alternatives. Adequate but with a clear gap.

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