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

Annotations already mark it non-read-only, non-destructive, closed-world. The description adds real context beyond them: it creates no TikTok mutation, it returns a single-use approval_ref, and the change is bounded/tenant-owned in advertiser-currency units. It does not, however, describe the idempotency or run_id lifecycle.

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 sentences, front-loaded with the core purpose and no filler. The non-mutation disclaimer and the adset/ad_group alias note each carry distinct, necessary 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?

No output schema and a complex 7-required-param tool, so the description carries more burden. It covers the key behavioral contract (no TikTok mutation, single-use ref) but leaves the idempotency_key, run_id, and rule_id_and_version semantics unexplained, which an agent needs to call it 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?

With only 13% schema coverage across 8 params, the description must compensate, and it only clarifies two things: target_value is in advertiser-currency units and entity_type's adset is an alias for TikTok ad_group. run_id, entity_refs, idempotency_key, rule_id_and_version, and connection_context remain 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 ("Validate ... a budget change") plus scope (bounded, tenant-owned, TikTok campaign or ad-group) and the output (single-use approval_ref). It clearly reads as the prepare-phase counterpart to budget_confirm, though it never names that sibling explicitly.

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 description implies the prepare-then-confirm flow via the approval_ref return and "does not mutate TikTok," but it never states when to call this versus budget_confirm, bid_prepare, or approval_plan_prepare, nor any prerequisites. Usage is implied rather than spelled out.

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