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

Annotations already declare the safety profile (readOnlyHint=false, idempotentHint=true, destructiveHint=false), so the bar is lower, and the description still adds genuine context: the budget remains reserved after pausing. That is a real post-condition an agent could not derive from the structured fields. It does not, however, describe the response or what happens to serving/impressions.

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?

Two short sentences with zero filler; the scope constraint is front-loaded and the budget post-condition follows immediately. Nothing could be removed without losing information.

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 simple one-required-parameter state-change tool with full schema coverage, complete annotations, and no output schema, the description covers scope and the key side effect. Only the reversible/resume relationship and expected response are unaddressed, which are minor gaps here.

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 100%, so both ad_id and api_key (including the Bearer-header fallback) are already fully documented in the schema. The description adds no additional constraint or format detail about ad_id, so the baseline 3 applies.

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 ('Pauses') and resource ('an active ad'), plus enumerates the affected ad formats (Banner, Native, Paid Visits). This clearly separates it from create_ad or get_ad, but it never names archive_ad or resume_ad, which are the closest siblings an agent might confuse it with.

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?

Usage is only implied: the tool applies to 'active' ads, so an already-paused ad is out of scope, but that is left for inference. There is no explicit when-to-use, when-not-to-use, or pointer to resume_ad for reversing the action.

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