compare_campaign_metrics

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

No annotations are provided, so the description carries the full burden. It usefully discloses one behavioral trait — that output is neither ranked nor accompanied by a recommendation — and 'compare' implies a non-mutating read. However, it says nothing about permissions, whether metric values are normalized across campaigns, or error behavior when a campaign lacks the metric.

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; the constraining clause comes after the core action, and every word 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?

An output schema exists, so return values need not be described. That leaves a two-parameter read tool with 0% parameter coverage and no usage routing, which is roughly the minimum viable level of completeness.

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%, so the description must compensate for both parameters, and it largely does not. It hints at a 'metric' dimension but never names the default (roas) or explains the required 'campaigns' array element shape (additionalProperties: true, so its structure is entirely undocumented elsewhere).

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 ('campaign metric values'), and scopes the operation by excluding ranking/recommendation, which cleanly separates it from investigation-oriented siblings like investigate_campaign or analyze_growth_query. It does not name a sibling directly, so 4 rather than 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?

The clause 'without ranking or recommending' implicitly tells the agent when this tool is the right fit (raw side-by-side comparison rather than advice), but there is no explicit when-to-use statement, no prerequisites, and no named alternative for the ranking/recommendation case.

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