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

Annotations already declare readOnlyHint and openWorldHint, so the safety profile is covered. The description adds a useful no-booking confirmation and the coordinate/address caveat, but says nothing about auth, rate limits, or return behavior.

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?

Front-loads the key estimate and no-booking facts in one compact sentence. The trailing Stuart endpoint is minor implementation detail, but the overall definition remains tight.

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 read-only estimate with a rich input schema, it conveys the return unit (seconds) and non-booking behavior. However, with up to eight dropoffs and no output schema, it does not clarify whether the ETA is per-dropoff, for the final dropoff, or aggregate.

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 the nested schemas document pickup, dropoffs, contact details, coordinates, and package type. The description's coordinate note mostly restates what the schema already says rather than adding new semantics.

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?

Names a specific verb (estimate) and resource (dropoff ETA to the destination address), and the destination/dropoff wording separates it from pickup ETA in the sibling set. It stops short of explicitly naming an alternative, so it is not quite top-tier.

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?

Says nothing is booked, which implies this is a non-committal estimate rather than create_job. But it does not state when to choose it over stuart_estimate_pickup_eta or stuart_estimate_price.

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