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

Annotations already declare readOnlyHint, idempotentHint and openWorldHint=false, so the safety profile is covered. The description adds genuinely useful behavioral context beyond that: the output includes lift/%/share metrics and annotations (deploys, posts, emails) are drawn from the preceding 24h window, which tells the agent the scope of the analysis.

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?

A single front-loaded sentence that leads with the core purpose ('ranked causes for one spike') and packs the remaining detail into a compact parenthetical. Dense but with no filler sentences.

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 usefully enumerates what is returned (ranked dimensions with lift, %, share, plus recent annotations), which is what an agent needs to judge relevance. The main remaining gap is the undocumented spike_id input.

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 only 50%: the domain parameter is documented in the schema, but spike_id has no description anywhere. The description does not explain what a spike_id is, where it comes from, or how it relates to the returned ranking, so it fails to compensate for the coverage gap.

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 states precisely what the tool produces for a single spike: ranked causes across referrers/UTM sources, landing pages and custom events, with lift, percentage and share. It is clearly the 'explain one spike' counterpart to find_traffic_spikes, though it never names that sibling explicitly.

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?

There is no explicit when-to-use guidance, no prerequisite (e.g. 'obtain spike_id from find_traffic_spikes'), and no alternatives named. The required spike_id and the 'one spike' phrasing only weakly imply the workflow.

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