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

With no annotations provided, the description carries the full burden and adds useful behavioral context: dry_run previews the diff without applying, updates are partial, budgets are in cents, and targeting is ad-set-only. It stops short of stating permissions, immediate application of changes, or error behavior, but it is substantially transparent for a mutation tool.

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, no filler, front-loaded with the core purpose and then the most decision-relevant usage rules. Every sentence earns its place.

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 tool with 5 parameters and no output schema or annotations, the description adequately covers what to send, how to use dry_run safely, and key constraints. It does not describe the success response format or explicit error handling, but that is a minor gap given the rest of the context.

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 20%, but the description compensates by defining the `updates` object semantics, dry_run behavior, budget units and placement rules, status values, and targeting scope. This adds meaning beyond the bare schema properties.

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 ('Edit'), a precise resource ('existing Meta campaign, ad set, or ad'), and enumerates the mutable fields. This clearly separates it from create tools and from Google update tools by naming Meta 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?

Gives clear operational context: only changed fields should go in `updates`, dry_run previews without applying, and budgets/targeting have entity-type restrictions. It does not explicitly name alternative tools for exclusion, but the 'existing' wording and field list imply when it should be used over creation tools.

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