Compare metrics grouped by platform, account, campaign, cross-campaign or date

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

Annotations already cover the safety profile (readOnlyHint=true) and openness (openWorldHint=true). Beyond that the description adds only the HTTP route, saying nothing about whether comparison requires a lookback window, what comparePrevious changes, or how results are shaped when groupBy=cross_campaign.

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 with no filler, but it is largely a copy of the title plus an endpoint path, so much of its brevity comes from saying almost nothing. The endpoint reference is the only content not already present in structured fields.

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 tool whose sole argument is a nested object with nine undocumented properties, no output schema, and a real ambiguity around comparison semantics, one sentence is far from sufficient. An agent cannot determine valid date ranges or the effect of lookbackDays and comparePrevious without guessing.

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 0% across a nine-property nested body, and the description rescues none of it: clientId, currency, firstParty, lookbackDays and comparePrevious get no meaning at all, and from/to date formats and range limits are unstated. The only parameter content is a restatement of the groupBy enum that the schema already enumerates explicitly.

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 ("Compare") and resource ("metrics") plus the available grouping axes, which is enough to distinguish this from list-style siblings like analytics_breakdown or analytics_timeseries. It never explicitly differentiates itself from those siblings, so it stops short of a 5.

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 statement of when to choose this over analytics_breakdown, analytics_timeseries, analytics_pacing or analytics_digest, and no prerequisites or exclusions. The only usage signal is the implied "use this when you want comparison", which the agent must infer from the grouping options alone.

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