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

Annotations already declare destructiveHint=true and readOnlyHint=false, but the description adds the crucial asymmetry the agent cannot get from annotations: decreases apply immediately while increases are staged behind a preview plus confirm=true. It also notes the value is in account currency, which affects how the agent should phrase the request. It does not state reversibility, required permissions, or what the preview card contains.

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 compact sentences, front-loaded with the resource and scope, then the operational caveat. No filler or repetition; the parenthetical about lifetime budget is slightly dense but earns its place by preventing a wrong assumption.

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 destructive, 7-parameter mutation with no output schema, the definition covers the two most important things an agent needs (level semantics and the preview/confirm flow). Gaps remain: how `id_or_name` resolves, what the preview returns, and how folder/account scoping interacts with account selection are all unaddressed.

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 only 43%, so the description has to carry weight: it does explain the semantics of `budget` (daily vs lifetime vs campaign cap, currency) and `confirm`, and implicitly the `level` enum. It says nothing about `id_or_name` (ID vs name matching), `folder`, `account`, or `language`, leaving four of seven parameters 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 and resource (change budget) and disambiguates what 'budget' means at each level: adsquad daily/lifetime budget vs campaign daily cap, in account currency. That level-specific framing matches the `level` enum and separates it from bid/status siblings conceptually, though it never names an alternative tool such as snapchat_update_bid.

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 second sentence gives real invocation guidance for the increase path (preview first, then confirm=true after the user's yes), which is genuinely useful. However there is no guidance on when to reach for this versus snapchat_update_bid, budget_status, or google_ads_update_budget, so routing between siblings is still left to inference.

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