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

Annotations already declare destructiveHint=true and idempotentHint=false; the description adds the concrete reason — that duplicate names are not detected server-side, so repeat calls can silently create duplicates. It also notes the new list is empty. It doesn't describe what is returned (e.g., new list ID), which limits follow-up use.

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 tight sentences plus the endpoint, with the WRITE marker and the core action front-loaded. Every sentence carries information: action, duplicate caveat, remediation step, endpoint.

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 single-parameter mutation with rich annotations, the description covers the main risk (duplicates) and the pre-check. The only omission is the return value, which matters since there is no output schema and the agent may need the new list's identifier.

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% and only one parameter (name) exists, with its own description and length bounds. The description adds nothing beyond confirming the list is created empty; baseline 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?

States a specific verb and resource ("create a new, empty sub list") and prefixes it with WRITE, making the mutation nature unmistakable. It is clearly distinguishable from siblings robly_list_sub_lists and robly_rename_sub_list.

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?

Explicitly instructs the agent to check robly_list_sub_lists first, because Robly won't report duplicates. That is real routing guidance to a named sibling, though it covers only the duplicate pre-check rather than broader when-not-to-use conditions.

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