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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the safety profile is known. The description adds meaningful behavioral context: the tool returns aggregated metrics, uses a default 30-day window, and enumerates the exact dimensions and aggregates returned. This goes beyond what annotations capture.

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?

The description is information-dense without being bloated. It front-loads the core purpose and prerequisite, then lists return fields, then gives the primary use case and alternative. Every sentence 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?

Given no output schema, the description compensates by listing all key return fields and dimensions. It also covers how to obtain the required id, the meaning of the optional `days` parameter, and the sibling tool to use instead for campaign-level metrics. Nothing essential for a read-only metrics 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 description coverage is 100%, so the schema already documents both `id` and `days` fully, including defaults, bounds, and suggested values. The description reinforces the id origin and default window, but adds little semantic value beyond the schema; therefore the baseline 3 is 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?

States a specific verb ('Get'), a specific resource ('aggregated click analytics for a specific short URL'), and a clear scope ('over a time window'). It also distinguishes itself from the campaign-level sibling by explicitly naming nevent_get_short_url_campaign_metrics and limiting this tool to individual tracking links.

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?

Provides explicit sequencing guidance: use after nevent_list_short_urls to obtain the `id`. It also gives the exact use case ('performance analysis of individual tracking links') and names the alternative for campaign-wide aggregation. The agent receives clear when-to-use and when-not-to-use direction.

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