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

Annotations already declare readOnly=false, destructive=false, idempotent=true, openWorld=true, so the safety profile is covered. The description adds genuinely non-structured behavior: watches are capped by existing plan limits, refreshes are driven by existing platform jobs, and no custom cadence is guaranteed — useful expectations the agent cannot get from annotations. It stops short of stating auth/permission needs.

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 short sentences, front-loaded with the action and object, no filler. The trailing "Reuse idempotencyKey" is terse to the point of being slightly cryptic, and the cadence caveat could be tighter, but overall the structure is efficient.

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?

An output schema exists, so return values need not be explained, and the behavioral context around plan limits and refresh cadence is a real addition. However, with five required parameters at 0% schema coverage and no discriminative usage routing, an agent is left under-equipped to invoke 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?

Schema description coverage is 0%, so the description carries the full burden for five required parameters. It only gestures at advertiser selection ("a selected public advertiser") and idempotencyKey reuse; it says nothing about brandId, source (meta/tiktok enum), advertiserId format, or advertiserName, leaving most parameters undocumented.

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+resource ("Create a watch") against a specific object ("a selected public advertiser"), which cleanly separates it from get_ad_watch, delete_ad_watch, and list_ad_watches. It scopes the operation ("within this brand's existing plan limits") but never names the sibling tools it is distinct from.

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?

There is no explicit when-to-use or when-not-to-use guidance and no alternative tool is named despite create/get/delete/list_ad_watch siblings existing. "Reuse idempotencyKey" is parameter advice, not usage routing, so the agent must infer context on its own.

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