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

Annotations already declare the write, destructive, open-world and non-idempotent profile, and the description reinforces the write nature with a "[write]" tag. It adds genuinely useful return-value context ("the result has its id and uuid") that the annotations do not cover, but says nothing about permissions, duplicate-title handling, or why a creation is flagged destructive.

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 short sentences, front-loaded with the operation type and purpose, with the follow-up tool and the tricky parameter definition trailing in priority order. No filler, though the backticked parameter name mid-sentence makes the second sentence slightly harder to scan.

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?

For a three-parameter creation tool with no output schema, the definition covers purpose, the population workflow, the return identifiers and the one non-obvious parameter. Only edge behavior (duplicate titles, required permissions) is unaddressed, which is minor at this complexity.

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 0%, so the description must carry the load; it explains the least obvious parameter in real detail by defining wp_list_country as the calling code (e.g. 90) that completes national numbers starting with 0. wp_list_title and wp_list_description are left to their names, which is a minor but real gap.

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?

States a specific verb+resource ("Creates an empty saved WhatsApp recipient list") and immediately clarifies scope by saying the list is empty and that the result carries an id and uuid. The WhatsApp qualifier distinguishes it from the sibling list-creation tools for SMS, email, Telegram and VoIP without needing to name them.

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?

Gives clear next-step context: the list is created empty and should be populated with add_wp_list_members, which implies this tool is the prerequisite for that one. It does not state exclusions (e.g. use edit_wp_list to rename an existing list), so it stops short of full when/when-not guidance.

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