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

Annotations already declare readOnlyHint, idempotentHint and destructiveHint=false, so the safety profile is covered. The description adds genuinely useful operational context beyond that: the 'act_123' ID format constraint and the returned spend-status field, which help the agent chain calls correctly.

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 sentences, zero waste. The core purpose is front-loaded and the sequencing/ID-format constraints follow immediately after.

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 description should carry return-value meaning; it names currency and spend capability but does not enumerate the full record shape (e.g., name/ID fields). Still sufficient for a 0-param read tool whose annotations cover safety, but slightly short of complete.

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?

The tool takes zero parameters, so the baseline is 4; there is no parameter syntax the description needs to explain. It does usefully clarify the account-ID format the agent will encounter downstream.

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 (List), resource (Meta ad accounts this agency can manage), scope (accounts under this agency), and the key return fields (currency, spend capability). 'Meta' in the description distinguishes it from the generic ads_* siblings such as ads_list_accounts, so an agent can identify the right tool without opening schemas.

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?

'Call before anything else Meta' is an explicit sequencing/prerequisite directive, which is exactly the usage guidance an agent needs given many sibling Meta tools. It also warns that ad account IDs must originate here, telling the agent when this call is mandatory rather than optional.

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