Turn the head

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

Adds substantial behavior beyond the annotations: it discloses the side effect of starting the simulation, that setting an angle switches the head to manual mode, the approx. 180°/s servo speed, and the full hill-climbing/rescan loop with the caveat that light sensors are directional and mounted on the head. This is exactly the context readOnlyHint=false alone 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?

Purpose and prerequisite are front-loaded, followed by the two parameter behaviors in the order they appear in the schema. The parentheticals are dense but every clause (speed, sign, rescan behavior) supplies information not available elsewhere.

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 2-parameter, no-output-schema tool with zero schema descriptions, the description covers everything needed to call it correctly in either mode, including the simulation-start side effect. The only gap is the default/empty-argument behavior.

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 0%, so the description carries the full burden and does it well: it documents the −90…90° range, the (+ = right) sign convention, and the complete semantics of track_light. It omits defaults and the interaction when both parameters are passed, keeping it short of 5.

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 ("Control the Head module (pan servo)") and immediately distinguishes itself from get_head and set_module by naming the required prerequisite. An agent can tell this drives hardware rather than reads state without opening the schema.

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?

Gives the prerequisite (set_module head first) and clearly separates the two usage modes: an explicit angle for manual positioning versus track_light=true for autonomous light-following. It does not say what happens when both or neither are supplied, and names no sibling alternative, so not a full 5.

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