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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered. The description adds real behavioral context: the fixed 7-day window, how avg_daily_spend handles younger campaigns, how the utilization ratio is computed, and how shared budgets are attributed — none of which is in the annotations.

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?

Front-loaded with purpose and window before formulas and field list; every sentence carries information. It is dense and formula-heavy but not padded, and the field enumeration is somewhat redundant given an output schema exists.

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 an output schema present, return values need not be explained, yet the description lists them anyway; combined with the window, formulas, and parameter note, an agent can invoke this correctly. Slight redundancy rather than a completeness gap.

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% for the single workspace parameter, so the description must compensate, and it does: it defines workspace as the customer workspace slug and notes it is optional when only one workspace exists. That is the meaningful semantic an agent needs for the only parameter.

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 names a specific verb/resource combination (daily budget, actual spend, utilization per campaign) and pins down the exact reporting window (last 7 complete days, excluding today). It also lists the returned metrics, so an agent knows precisely what this tool answers versus generic performance tools.

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?

It explicitly routes the agent to budget_pacing for the monthly course, which gives a clear positive alternative. It also explains the shared-budget caveat, but does not state exclusions relative to ads_campaign_performance or ads_update_campaign_budget beyond that single pointer.

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