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

Annotations cover the safety profile (readOnly, idempotent, non-destructive), so the bar is lower, yet the description still adds real context: auth requirements and plan-gated behavior ('by hour of the day on plans with time-of-day analytics'). It doesn't discuss result sparsity when the plan lacks a breakdown, but the additions exceed the annotation baseline.

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?

Three sentences, front-loaded with what data comes back, then prerequisites, then the alternative. No filler; each sentence routes or constrains the caller.

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 enumerating the returned metrics. Auth, identifier formats, plan limits, and the sibling alternative are all covered, so nothing an agent needs to invoke it correctly 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 baseline is 3, but the description adds meaningful context: which identifier forms are accepted (short link, ending, or id) and that hour-of-day data only appears on certain plans, which explains gaps in the 'days' scoped result.

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 ('clicks and QR scans for one of the user's own Snip links') and enumerates the returned breakdowns (totals, by day, by hour, top countries, referring sites, devices). It explicitly distinguishes itself from get_account_stats, so the agent can choose correctly without opening either schema.

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?

Names the prerequisite ('Needs the user signed in to Snip ... or an API key') and the alternative with its triggering condition ('For every link at once, use get_account_stats'). Both when-to-use and when-to-use-something-else are explicit.

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