get_account_info

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

With no annotations, the description carries the full burden. It discloses that access_token is optional and uses a cached token if omitted, that fields replace the default set, and it explains the precise meaning of 'balance' for prepaid accounts (common in Brazil). This goes well beyond basic read-only behavior and provides critical financial semantics.

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 concise opening and structured Args breakdown. Every sentence adds valuable detail—especially the prepaid account note about Brazilian accounts—without excessive padding or repetition. It is appropriately sized for the tool's complexity.

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?

Given the tool's simplicity (3 params, output schema present), the description is exceedingly complete. It covers parameter formats, defaults, field replacement semantics, and a geographic edge case. The output schema handles return values, so the description's job is to provide usage context, which it does exceptionally.

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 must explain all parameters. It does so thoroughly: account_id includes the required format, access_token explains its optionality, and fields not only lists examples but explains that they replace the defaults and describes the default field set. It even clarifies edge-case behavior for prepaid accounts.

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 opens with 'Get detailed information about a specific ad account,' which clearly states the verb, resource, and scope. The use of 'specific' distinguishes it from sibling tools like get_ad_accounts (which lists accounts), making the tool's purpose unambiguous.

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 description provides clear context for fetching a single account's details, including the optional access_token and customizable fields. It never explicitly names alternative tools for listing accounts or says when not to use this tool, but the 'specific' wording strongly implies its appropriate use case.

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