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

No annotations are provided, so the description carries the full burden of behavioral disclosure. It conveys that this is a mutation tool and lists use cases, but it does not explain merge semantics, whether updates are partial or full replacements, permission requirements, side effects, reversibility, or what the response 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?

The description is well-structured with a clear summary, 'WHEN TO USE' bullets, and a concrete example. It is front-loaded, every section earns its place, and the example efficiently demonstrates the expected invocation shape.

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?

This is a complex tool with 17 parameters, nested objects, no annotations, and no output schema. The description covers the core update flow well, but it leaves many parameter mechanisms unexplained (e.g., cancellation, idempotency, package changes, webhooks), making it incomplete for full correct invocation in all scenarios.

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 12%, so the description must compensate. It adds useful semantics by mapping to fields like status, budget, targeting, and dates, and the example clarifies the important `updates` object shape. However, many top-level parameters such as packages, paused, canceled, cancellation_reason, idempotency_key, and webhook settings remain unexplained.

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 states a specific verb and resource: "Update an existing media buy," and further specifies the modifiable dimensions: budget, targeting, schedule, or status. This clearly distinguishes it from creation and read tools such as create_media_buy and get_media_buys by emphasizing 'existing' and 'update.'

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 'WHEN TO USE' section provides concrete scenarios: adjusting budget mid-flight, pausing/resuming, changing targeting, and extending dates. It gives clear context for when the tool is appropriate, though it does not explicitly state when not to use it or name alternative tools.

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