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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description adds genuinely new behavior: an entitlement gate ('Requires Pro tier or higher') that determines whether the call will succeed at all. It does not mention pagination or any limits on the returned analytics, which keeps it short of a 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?

Two sentences, front-loaded with the core action and its output dimensions, followed by the entitlement constraint. No restatement of the title and no filler.

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?

The tool is a simple two-parameter read with no output schema, and the description conveys both the input scope (one link) and the shape of the result (agents, vendors, daily trends). Only minor gaps remain — no mention of result size or time-zone/day-boundary semantics for the trend data.

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% — both short_code and period_days (1-90, default 7) are fully documented in the schema. The phrase 'click trends by day' hints at how period_days is interpreted, but adds no format or granularity detail beyond the schema, 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?

Specific verb+resource: 'Get AI-agent click analytics for a specific link', then it enumerates the exact dimensions returned (which agents, vendors/frameworks, daily trends). That scope (per-link, agent-specific) distinguishes it from get_link_stats and get_agentlink_account_stats without needing the schemas.

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?

Clear context: requires a short_code for one specific link, so an agent knows it's the per-link variant, and it states the 'Pro tier or higher' prerequisite up front. It does not explicitly name the sibling (get_agentlink_account_stats) to use for account-wide data, so the alternative routing is left to inference.

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