list_merge_fields

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

No annotations are provided, so the description carries the full burden of behavioral disclosure. It only says 'List' without stating that this is a read-only operation, that it is paginated (though count/offset parameters imply it), what the default page size is, or any return characteristics. The description adds minimal behavioral context beyond the tool's name.

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 a single concise sentence that front-loads the action and resource. Every word earns its place, with no fluff, repetition, or irrelevant details.

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 simple and the schema covers all parameters with clear descriptions, including default count and offset meaning. However, with no output schema and no annotations, the description does not explain the response structure or any behavioral nuances. It is minimally complete but lacks the richness needed to fully prepare an agent for invocation without additional assumptions.

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?

The input schema provides full descriptions for all four parameters, including the 'list_id' required audience ID, the 'type' filter, and 'count'/'offset' pagination controls. The description adds only the clarification that merge fields are 'custom fields', which is marginal. With 100% schema coverage, the 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 uses the specific verb 'List' with the resource 'merge fields (custom fields)' and includes the scope 'for an audience'. This clearly separates it from sibling tools like get_merge_field (single field), create_merge_field, update_merge_field, and delete_merge_field.

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 (list all merge fields for a given audience) but does not explicitly state when to use this tool versus alternatives or provide any exclusion criteria. The usage context is inferable from the verb and sibling names, but not spelled out.

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