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

Annotations already cover the safety profile (readOnlyHint=true, destructiveHint=false), and the description adds useful behavioral context: the tool returns selectable values for advanced widget settings/filters, and those values are meant to populate datasource keys. The 'and so on' wording also aligns with openWorldHint=true. No contradiction or hidden surprise.

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?

Two sentences, zero filler, with the core action front-loaded and the clarifying relationship to describe_datasource in the second sentence. The examples are compact and informative rather than redundant.

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 is complete for this tool's role: it states what is returned, how it relates to describe_datasource, and gives examples. With an output schema present and annotations covering safety, no critical operational detail is missing. It could explicitly mention the need for client_id/datasource_id context, but the schema already supplies that.

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 100%, so the schema already documents datasource_id, client_id, resource, and params. The description adds some orientation by mentioning campaign/ad-set-style resources and pointing to describe_datasource for key naming, but it does not add significant parameter-level meaning 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 description uses a specific verb and resource: 'List the selectable values behind a widget's advanced settings and filters,' and names concrete examples. It also explicitly distinguishes itself from describe_datasource, making its purpose unambiguous even among many sibling list_* tools.

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 gives an explicit workflow: describe_datasource tells you WHICH advanced keys are required, while this tool returns the values to fill them with. This clearly routes the agent between the two tools and leaves no ambiguity about when this tool is the right choice.

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