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

No annotations are present, so the description carries the full burden. It provides useful behavioral context by stating 'Live Meta API call' and 'Not cached', which informs the agent that results are fresh but may be slow or subject to API failures. However, it does not disclose other significant behaviors like rate limits, pagination, or potential large result sizes.

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?

A single, well-structured sentence that front-loads the purpose and scope. Every word earns its place without repetition or fluff. The 'Not cached' warning is a useful, distinct addition.

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?

The description gives enough to understand the core function, but with 12 parameters and no output schema, more guidance would help—such as what the response looks like, pagination expectations, or a note about common breakdown combinations (e.g., max 2 dimensions). The schema covers parameter definitions but not the overall call context.

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 75%, so the schema already documents most parameters in detail. The description adds no extra meaning beyond the schema; it just mentions 'spend and performance metrics' and example dimension values, which are already listed in the parameter descriptions. It does not compensate for the remaining undocumented parameters.

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 clearly states a specific action ('get spend and performance metrics'), a resource ('Meta API call'), and the key distinguishing feature ('sliced by demographic or placement dimensions'). It immediately differentiates this tool from the sibling adsap_get_insights without requiring schema inspection.

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 phrase 'sliced by demographic or placement dimensions' implies when to use this tool (when breakdowns are needed), but it never explicitly names the alternative or states any exclusion condition. The agent must infer the choice based on the name and sibling list rather than being explicitly guided.

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