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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false, and openWorldHint=false, so the safety profile is settled. The description still adds real value by disclosing a precondition — the golfer must be linked to a coach — and by enumerating what data is returned (plans, drills, targets, progress per item). It stops short of saying what happens when no coach link exists.

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?

A single sentence, front-loaded with the usage trigger and then the payload, with no filler or repetition of the title. Every clause earns its place.

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 input parameters and no output schema, the description needs to convey only when to call it and roughly what comes back — both are covered. The one gap is the empty/error state (no coach link, no active plans), which an agent may need to interpret an empty result correctly.

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 zero parameters, so there is nothing for the description to disambiguate beyond the implicit scoping to the linked golfer. Baseline 4 applies for a parameterless tool.

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-resource relationship: it retrieves what a coach assigned — active Coach plans, drills, targets, and per-item progress. That is far more specific than the title 'Coach's plan'. It doesn't explicitly contrast with siblings like practice_plan or progress, so an agent must infer that those cover self-directed plans and general progress.

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 'Use this when a linked golfer asks what their coach assigned' phrasing gives a clear triggering condition and an implied scope (coach-assigned content only). No exclusions or named alternatives are given, so the agent isn't told what to use if the golfer wants self-created plans or raw progress data.

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