Get Reach Estimate

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

Annotations already declare readOnlyHint=true and destructiveHint=false. The description adds transparency by stating it returns estimated daily reach and audience size, and that optimization_goal (e.g., REACH, LINK_CLICKS, IMPRESSIONS) affects the estimate. No contradiction with 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 front-loads a one-sentence purpose, then provides a structured args list and a return line. Every sentence earns its place with no wasted words or redundancy.

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 read-only estimator with 4 parameters and no output schema, the description covers required parameters, optimization_goal semantics, and the return value. It does not mention pagination or rate limits (likely inapplicable) and could reference the sibling meta_get_delivery_estimate, but overall it is sufficient for an agent to call the tool correctly.

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 only 50%, but the description supplies meaning for ad_account_id, targeting_spec (same format as ad set targeting), and optimization_goal with concrete examples. This compensates well for missing schema descriptions. response_format is already described in 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 description clearly states 'Estimates the potential reach for a targeting specification' with a specific verb and resource. It does not explicitly differentiate from the sibling meta_get_delivery_estimate, so it misses the full sibling distinction.

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 implies usage for estimating reach for a targeting spec and provides helpful context like 'same format as ad set targeting' and examples for optimization_goal. However, it gives no explicit when-to-use guidance or exclusions relative to similar tools such as meta_get_delivery_estimate.

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