Guard the goal

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

Annotations already declare destructiveHint=true and readOnlyHint=false, so the agent knows this is a mutating action. The description adds real behavioral detail (position 25 cm in front of the goal, slide between ball and centre, end early on catch), but it never explains what the 'destructive' trait means here - e.g. that it takes over control for up to `seconds` and preempts other commands.

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?

One front-loaded sentence with the verb first and the mechanics following; the parenthetical clarification earns its place. Slightly long and clause-heavy but free of filler.

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?

No output schema exists, and the description is behaviorally complete for the motion itself, including the termination condition. However, for a destructive control-taking tool it omits blocking/timeout semantics tied to `seconds`, and gives no parameter interpretation against a 0%-coverage schema.

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 description coverage is 0% across 3 parameters, so the description must compensate and largely doesn't. The prose touches goal-side logic ('the blue team guards the orange goal') but never explains the `goal` enum values including the default `defend`, and `seconds` and `speed_percent` are not mentioned at all.

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 states a specific verb and behavior ('Play goalkeeper for a while') and spells out the stand-and-slide mechanics, so the agent knows this is a high-level autonomous behavior, distinct from primitive siblings like move/turn. It does not name a contrasting sibling, but the purpose itself is unambiguous.

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?

Usage is implied by the phrase 'Play goalkeeper for a while', suggesting a defensive situation, but the description never says when to choose this over manually combining move/face_object/stop, nor when not to use it. No prerequisites or alternatives are named.

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