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

Annotations already declare this is a destructive, non-read-only, open-world mutation, so the bar is lower, yet the description adds genuinely non-obvious behavior: the asymmetric confirmation flow for increases versus immediate decreases and the preview requirement. It stops short of saying what happens if confirm is omitted (error vs silent no-op) or whether the preview itself is idempotent.

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 sentences, each carrying distinct payload: the first defines scope and unit, the second defines the mutation and approval behavior. The most decision-relevant fact (immediate vs preview-then-confirm) is front-loaded in the second sentence with no filler.

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 7-parameter mutation tool with no output schema, the description covers the safety-critical path and even references the returned preview. It is slightly thin on how id_or_name is resolved (name collisions, whether ID is preferred) and on account/folder context when multiple accounts are enabled.

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 coverage is only 43%, and the description compensates by explaining the semantics of the three most consequential parameters: level (campaign vs ad group), budget (interpreted in account currency and matching the existing daily/lifetime setting), and confirm (required only after a user's yes on increases). The remaining parameters (id_or_name resolution, folder, account scoping) are left to the schema, which documents only folder and account.

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 and resource ("change the budget of a campaign or ad group") and adds scope (daily vs lifetime, account currency), which is far more informative than the bare title. It does not explicitly distinguish itself from near-neighbours like tiktok_update_bid or the other platforms' *_update_budget tools, relying on the prefixed name to do that work.

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 gives useful operational context: decreases apply immediately while increases require a confirm=true follow-up after user approval, which effectively tells the agent how to sequence calls. However, there is no guidance on when to prefer this tool over budget_status/budgets_at_risk for inspection, or over tiktok_update_bid when both bid and budget change.

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