get_audience_reach

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

With no annotations, the description carries the behavioral burden. It discloses that the metric is approximate and explains the exact formula used (unique members reached / total target audience size). It also notes the date range limitation. It does not mention authentication requirements, response structure, or rate limits, but the read-only nature is implied by 'Shows'.

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?

Three sentences plus a note, front-loaded with the primary purpose. The metric formula adds specificity without excess, and the date-range note is essential. 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?

Description explains the metric and its calculation, which helps interpret results. However, no output schema exists and the description does not specify the response structure beyond the metric name. It also doesn't mention default behavior when filters are omitted, so an agent might need to infer response format.

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 100%, so parameters are already documented. The description repeats the 92-day constraint already present in the schema but adds nothing about accountId, campaignIds, or campaignGroupIds. Baseline of 3 applies.

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 states a specific verb and resource: 'Shows unique member reach and native audience penetration for campaigns.' This clearly distinguishes it from siblings like get_campaign_performance and get_audience_demographics by focusing on reach and penetration metrics.

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 provides clear context for when to use this tool – to understand what percentage of the target audience has been reached. It also notes a critical constraint (date range ≤ 92 days). However, it does not explicitly name alternative tools or exclusions.

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