Walk the duck

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

With no annotations provided, the description carries the full burden and delivers: it discloses value clamping (±0.25 m/s linear, ±1 rad/s yaw), the fact that the call blocks until the walk finishes, the deadman safety mechanism that stops the duck if the server dies, and the battery/fallen refusal conditions. This is rich behavioral context well beyond what a schema could 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?

Every sentence in the description earns its place: the intent definition, the safety clamps, the timing behavior, the interruption and deadman guarantees, the follow-up monitor suggestion, and the refusal conditions. It is compact, well-ordered, and front-loads the core action before secondary details, with no redundant phrasing.

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 robot-motion tool with no output schema and no annotations, this description is remarkably complete: it explains blocking semantics, failure/refusal conditions, safety fallbacks, and where to get results afterward. An agent has everything needed to invoke it correctly and know what to expect, making the description self-sufficient.

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%, so the baseline is 3. The description adds value by stating the physical clamping limits for vx/vy/wz, which are absent from the schema itself, and by confirming the duration default and maximum in plain language. It doesn't add per-parameter syntax details, but the clamping information meaningfully supplements the schema, so 4 is appropriate.

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 opens with 'Send a velocity intent: vx forward m/s, vy sideways m/s, wz yaw rad/s' — a specific verb ('send'), a clear resource (the duck), and the exact axes of motion. It distinguishes itself from sibling tools by explicitly pointing to duck_stop for interrupting and duck_monitor for checking progress, so an agent can tell at a glance what this tool uniquely does.

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 gives explicit usage conditions, including when the tool is refused ('below 15% battery or when fallen'), the default and maximum duration, and direct guidance on alternatives: 'duck_stop interrupts it at any time' and 'Call duck_monitor afterwards to see how far it got.' This is clear when-to-use and when-not-to-use guidance that routes the agent to the correct sibling.

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