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

With readOnlyHint and destructiveHint=false already covering safety, the description adds substantial behavioral context: unconnected platforms are returned as connected:false, connecting only happens in the REACH web app, expired lists cannot be exported, each platform has a minimum record count, and only lists with Online Audience output are eligible. These are business rules not present in annotations or schema.

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 front-loaded with purpose and then organized into parameter-driven use cases and eligibility constraints. Every sentence is informative, though the middle paragraph is dense and could be slightly tighter for readability.

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 an output schema exists, return-value details are not required in the description. The description nevertheless covers eligibility rules, connection handling, and the relationship to export_list_to_ads, making it complete for an agent to call and interpret this read-only discovery 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 coverage is 100%, so parameters are already well documented. The description still adds cross-tool semantics: platform+account_id yields Ad Platform Audiences that export_list_to_ads can consume via audience_id, and list_id produces per-platform eligibility with failure reasons. This meaningfully exceeds the schema alone.

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 uses a specific verb ('Discover where a list can go in an Ad Platform Export') and enumerates exactly what is returned: supported platforms, connection status, ad accounts, existing audiences, and per-list export eligibility. This clearly distinguishes it from the sibling export_list_to_ads, which performs the actual export, and from ads_export_status.

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?

It explicitly states the conditional calls: pass platform and account_id to retrieve that account's existing Ad Platform Audiences, and pass list_id to check exportability with reasons. It also explains what to do when a platform is unconnected (direct the user to the REACH web app Integrations page), leaving no ambiguity about when and how to use this tool versus export_list_to_ads.

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