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

Annotations already indicate readOnlyHint=true, idempotentHint=true, and destructiveHint=false. The description adds useful context about high-cardinality fields and why the options cannot be embedded in schemas. No contradictions exist between the description and 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 two sentences long, front-loaded with the core purpose, and contains no filler or redundant material. Every sentence contributes meaning.

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 tool is a simple read-only options lookup with full schema coverage, rich annotation coverage, and an output schema. The description explains both the core function and appropriate use, making it complete for an agent to understand and invoke 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?

All 4 parameters already have complete descriptions in the input schema, so the description does not need to repeat parameter details. However, it also adds little beyond the schema; for example, it does not clarify which fields are valid or that `field` is semantically required despite the schema listing no required parameters.

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: 'Return allowed option values for Consumer Audience Builder (B2C Listgen) fields.' It clearly identifies the consumer/B2C scope, distinguishing it from the sibling b2b_listgen_options tool.

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 explicitly states when to use the tool: 'Use this tool when you need the valid values for large, high-cardinality fields too big to embed directly in tool schemas.' It provides a clear context but does not explicitly mention alternatives or when not to use it, such as pointing to the B2B sibling tool.

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