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

Annotations declare destructiveHint/openWorldHint, and the description goes well beyond them: passing multipliers forces bid_optimization=false, positive-only percentages enforced since 15/6/2026, batch capped at 25, and per-id/per-placement read-after-write verification. This is exactly the operational context an agent needs for an irreversible mutation.

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?

Purpose is front-loaded and every sentence carries operational value, but the single dense paragraph is run-on and some clauses (e.g. the placement alias list) restate schema content. Information-dense yet slightly overpacked for scannability.

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 complex nested mutation tool with no output schema, the description covers modes, limits, side effects, the optimization trade-off, and read-after-write verification. An agent has enough to call it correctly without guessing.

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 50% schema coverage, the description compensates strongly: it documents the single (campaign_id + patches) vs batch (items) shapes, the bid_optimization interplay, placement enum values with aliases, percentage semantics, and the 25-item cap. This adds meaning well beyond what the schema descriptors provide.

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 (Aggiorna) and resource (campagne Sponsored Brands ESISTENTI) plus the fields it mutates (budget, stato, ottimizzazione dell'offerta). Explicitly rules out the create case ("NON crea campagne nuove"), which cleanly separates it from the ads_create_* siblings.

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 explicit when-to-use and when-not-to rules: to optimize without cutting volume use placement multipliers, and to spend less on a placement lower keyword/target bids via ads_update_sb_keyword_bid/ads_update_sb_target_bid instead. Names the alternative tools directly and explains the single vs batch invocation paths.

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