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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the safety profile is covered. The description adds genuine value by itemizing the returned metrics (total/unique clicks, per-day, breakdowns by country, OS, device, browser, referrer, outcome), which is important since there is no output schema. It omits behavior on unknown slugs or empty ranges, hence 4 not 5.

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, front-loaded with the resource and scope, followed by the enumerated outputs. No filler or 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?

With no output schema, the description compensates by listing the return fields, and the schema covers date defaults. Minor gaps remain around empty results and error behavior for an invalid slug, but nothing essential to calling the tool is missing.

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 schema already documents slug, start and end with formats and defaults. The description only restates that the range is a date range and the target is one link — useful tie-in but no additional syntax or semantics beyond the schema. Baseline 3 applies.

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 names a specific verb+resource ('Clicks for one link over a date range') and enumerates the metrics returned, so an agent knows exactly what it retrieves. It doesn't explicitly contrast with close siblings like get_link_timeseries or get_account_stats, which is why it stops short of 5.

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 implied by 'for one link over a date range' — the agent can infer it is the per-link aggregate stats call. However, there is no explicit when-to-use/when-not guidance and no mention of the sibling alternatives such as get_link_timeseries for finer granularity or get_account_stats for account-level data.

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