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

Annotations already declare readOnlyHint, openWorldHint and non-destructive, so safety is covered. The description's real contribution is the field inventory and the 'no performance metrics' constraint, but it says nothing about pagination, result ordering, or whether archived/paused campaigns are included.

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?

Two tight sentences with zero padding: the payload description comes first, then the exclusion and the alternative. Every clause carries information an agent would otherwise have to guess.

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?

With no output schema, the field list is what makes the return shape predictable — that gap is closed well. Small residual gap: nothing states result volume, filtering, or ordering, which matters for a list tool on a single account.

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?

Only one parameter and schema coverage is 100% — the schema already explains the account id format, the msads_list_accounts reference, and the conditional-requirement rule. The description adds nothing parameter-specific, so the baseline 3 applies.

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 ('List campaigns for an account') and enumerates exactly which fields come back (id, name, status, type, daily budget, bidding scheme). It also pre-empts confusion with the similarly named performance sibling, so an agent can route without opening a schema.

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?

Explicitly scopes the tool to structural data and names the alternative (msads_get_campaign_performance) for spend and results, which is a genuine when-to-use rule. It stops short of covering other routing cases, such as how it relates to the generic get_campaigns sibling or when the optional accountId can be omitted.

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