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

Annotations already declare readOnlyHint=true and openWorldHint=true, so safety and external-dependency context is covered. The description earns credit for non-obvious behavioral traits: it discloses that paymentMethod is null specifically when Meta withholds it, and that amounts are in whole currency units rather than cents. Neither of these is derivable from annotations or schema, which is genuinely useful. It stops short of describing staleness, caching, or error behavior, so it sits at a solid 3.

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 compact sentences, front-loaded with the primary action and resource, and every clause carries distinct information (returned fields, null semantics, currency units). No filler.

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 single-entity read with readOnly/openWorld annotations and no output schema, the description covers what is returned and two important data quirks. However it leaves the required adAccountId parameter completely undocumented in both description and schema, and gives no usage routing to the many similar sibling tools. Adequate but with clear gaps.

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 coverage is 67%, so the schema already documents accountId and profileId with defaults; the description adds no parameter-level semantics. The third parameter, adAccountId, has no schema description at all and the description also says nothing about its act_<id> format or where it comes from. Baseline 3 with a partial gap that the description does not close.

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 clear verb+resource: 'Return one ad account' with a specific enumeration of returned fields (status, amount spent, spending limit, payment method presence). It distinguishes the single-account retrieval from the list-oriented siblings (ads_list_accounts, get_account) implicitly through 'one ad account', though it never names those alternatives explicitly.

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?

No when-to-use guidance at all. It does not tell the agent how this differs from ads_list_accounts, ads_get_tree, ads_get_insights, or the generic get_account, nor does it state prerequisites such as needing an adAccountId obtained from list_accounts. The agent must infer usage entirely.

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