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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the safety profile is covered. The description adds only the 'for this account' scope and nothing about what the comparison returns, how platforms are aligned, or any data-freshness caveats, so it contributes almost no behavioral context beyond the structured fields.

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?

The single sentence is front-loaded and free of filler, so it is structurally clean. But for a 17-parameter comparison tool it is drastically underspecified, which is a sizing problem rather than genuine conciseness.

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 needn't be spelled out, but the description still omits how the two platforms are parameterized, which identifiers are required, and how the date window is chosen. For a tool this complex with zero parameter documentation, the definition is far from complete.

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?

With 17 parameters and 0% schema description coverage, the description carries the full burden of explaining the inputs and explains none of them. It is impossible to tell from the definition how date_from/date_to, range_preset, days, sort_by, or the many account-identifier parameters (ad_account, page_id, ig_user_id, client_id, site_url) shape the comparison.

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 says what the tool does at a high level — it compares Google vs Meta ads for the current account — so the verb and resource are recoverable. However, it is essentially a restatement of the title 'Compare Google and Meta' and adds no differentiation from the sibling summary tools (google_ads_get_summary, meta_ads_get_summary) that also report ad performance.

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 guidance on when to use this comparative tool versus the per-platform summary or trends tools in the sibling list. No prerequisites, exclusions, or alternatives are stated; the agent must infer usage from the name alone.

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