Get Reach Estimate

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

Annotations already declare readOnlyHint=true, destructiveHint=false, so the agent knows it's a safe read operation. The description adds that the tool returns estimated daily reach and audience size, which is helpful but does not disclose additional behavioral traits beyond the annotations.

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 concise, front-loaded with the purpose, and efficiently lists arguments and returns. It is well-structured without unnecessary detail.

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 presence of a nested object (targeting_spec), optional parameters, and no output schema, the description provides the essential information to use the tool. However, it does not explain the 'response_format' parameter's purpose or behavior, which is a gap.

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 description adds meaning to the parameters: 'ad_account_id' as 'Ad account ID', 'targeting_spec' as 'Targeting specification (same format as ad set targeting)', and 'optimization_goal' with examples. The 'response_format' parameter is not mentioned, but schema description covers it partially. Overall, the description adds value beyond the schema.

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 title and description clearly state the tool estimates potential reach for a targeting specification, using a specific verb ('Estimates') and resource ('reach'). It is distinct from sibling tools like meta_get_delivery_estimate.

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 states the tool estimates potential reach for a targeting specification but provides no explicit guidance on when to use this tool versus alternatives like meta_get_delivery_estimate. Usage context is implied but not detailed.

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