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

With readOnlyHint=false the annotations only say 'not read-only'; the description adds the genuinely useful nuance that this call writes an approval draft but does not change delivery, and names the artifacts returned (approval_ref, plan_digest) that the confirm step consumes. It does not disclose whether the draft expires, requires permissions, or what happens on concurrent drafts.

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?

Three front-loaded sentences with the core action, the return artifacts, and the safety note packed in; little waste. The trailing 'Prefer entities_prepare_update for new work' is slightly cryptic and appended rather than integrated, but the description is well within an appropriate size.

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?

The workflow contract (prepare then confirm, no delivery change) is complete enough for correct invocation, and an output schema covers return values. However, with 0% parameter documentation and an ambiguous alternative-tool pointer, an agent still lacks guidance on how to fill the inputs correctly.

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% and the description never mentions adset_id, ad_account_id, daily_budget, or connection_context. Only 'daily-budget change' faintly implies the daily_budget parameter; the ID and connection_context parameters are entirely undocumented in both places.

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 ('prepare') plus a precise resource and scope ('one ad set daily-budget change'), and describes the two-phase action (read Meta settings, save an approval draft). This cleanly separates it from siblings adsets_prepare_bid_change and adsets_prepare_status_change without needing the schema.

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?

Gives a clear sequencing rule: apply only after approval via operations_confirm_adset_budget, and points to entities_prepare_update for new work. It lacks an explicit when-not-to-use condition (e.g., vs. campaigns_prepare_budget_change for campaign-level budgets), and the entities_prepare_update guidance is vague about what 'new work' means.

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