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 the useful fact that the series is daily and excludes breakdowns, but says nothing about date-range defaults, 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?

Two short sentences with zero filler; the core scope is front-loaded and the usage hint follows immediately.

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 3-parameter read-only list tool with full schema coverage and annotations, the description covers what the tool returns conceptually ('clicks per day'). A note on the result shape (date/count pairs) or behavior with no clicks would close the remaining 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 coverage is 100%, so slug, start and end (including the UTC YYYY-MM-DD format and default windows) are fully documented in the schema. The description only gestures at 'date range' and adds no meaning beyond it, so 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?

States a specific verb+resource+granularity: 'Clicks per day for one link over a date range'. The clause 'without the breakdowns' distinguishes it from the sibling get_link_stats, which presumably offers those breakdowns.

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?

'Use it for trends and charts' gives a clear positive condition, and 'without the breakdowns' implies the when-not case. However, it never names get_link_stats explicitly as the alternative, leaving the agent to infer the routing.

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