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

Annotations already declare readOnlyHint=true, so the description doesn't need to restate safety. It adds valuable behavioral context beyond annotations: OAuth authentication requirements, the lists:read scope, private-list inclusion, and the 401 response when no account is connected. This is meaningful disclosure for an API-facing tool.

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, no filler. The first sentence states the primary purpose and return contents; the second covers authentication and error behavior. All information is relevant and front-loaded.

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?

With no parameters and no output schema, the description still gives the agent enough to call the tool correctly: what it returns, whether private items are included, the required auth scope, and the failure mode. Nothing essential is missing for selecting or invoking it.

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 tool has zero parameters and schema coverage is 100%, so there is no parameter information needed. The description adds no parameter details, but none are required. Baseline 4 applies for zero-parameter tools.

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 ('Returns') and identifies the exact resource ('the connected user's own lists'), including the concrete fields returned (titles, visibility, item counts, URLs). It also clarifies scope by noting private lists are included, which distinguishes it from a generic list-all tool and from siblings like get_list that target a single 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?

The description clearly indicates when to use this tool: when the connected user wants their own lists, including private ones. It also states the prerequisite (connected ListDrop account with lists:read scope) and the failure signal (401). It does not explicitly name alternatives or exclusion conditions, but the context is clear enough for an agent.

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