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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint and destructiveHint=false, so the safety profile is fully covered without the description. The description adds useful payload context by enumerating the values returned (cap, spent, balance, currency), but says nothing about edge behavior such as accounts with no cap set or partial permissions.

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 opening fragment and the following sentence restate the same field list (spend cap, amount spent, balance), so roughly a third of the text is duplication. The intent sentence is front-loaded and useful, but the redundancy costs efficiency.

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 one-parameter, read-only lookup with no output schema, the description adequately conveys what the call returns and when to make it. The lack of any note on missing-cap or error states is a small residual gap rather than a blocking one.

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 a single required parameter and 100% schema description coverage (including the act_ prefix pattern and the pointer to list_ad_accounts), the schema carries the parameter meaning. The description contributes nothing about the id format or where to obtain it, so 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?

The description names a specific verb (Get) and concrete returned fields (spend cap, amount spent, balance, currency) for a named resource, the Meta ad account. It is distinguishable from budget/campaign siblings because it is explicitly about the account-level cap and balance rather than campaign budgets, though it never names a sibling to route against.

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?

"Use when user asks about account limits or remaining budget" gives a clear triggering condition tied to user intent, which is more than most definitions offer. It stops short of exclusions or naming an alternative (e.g. get_account_overview) for adjacent questions.

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