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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, closed-world), so the description's extra burden is low. It still adds real value by disclosing the account prerequisite ('Needs their WithBy account') and the shape of the result (road-order list with per-story length), which annotations cannot convey.

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 usage trigger before the mechanics and prerequisites. Every sentence carries distinct information: when to call, what is returned, account requirement, scope exclusion.

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 output schema and zero parameters, the description adequately covers what the agent needs: the trigger, the account requirement, and the returned content (road order, story length). It is slightly thin on what happens with an empty list or whether the list is per-user or shared, but nothing critical is missing for a simple read tool.

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 takes no parameters, so the baseline is 4 and there is no schema semantics the description needs to compensate for. The description correctly implies no filtering arguments are required.

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 ('Lists their WithBy next-drive list') and adds the ordering and payload ('road order with each story's length'), so the agent knows exactly what comes back. It does not distinguish itself from actual siblings such as save_for_drive or story, instead excluding unrelated domains (navigation, bookings), which limits sibling differentiation.

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?

'Use this when someone asks which stories they saved for their next drive, or which one comes first' gives a clear, concrete trigger tied to user phrasing. It also states a negative boundary ('Not for navigation or bookings'), though it never names the sibling tool an agent should call instead for saving or fetching a single story.

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