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

The readOnlyHint annotation already establishes that this is a safe reference operation. The description adds useful content scope by listing the returned material: update rule, hinted-answer exception, selection mechanics, tuning constants, and porting notes. It does not discuss auth or rate limits, but those are unlikely to be important for a read-only explanation tool.

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?

The description is front-loaded with the tool's identity and is reasonably sized for a complex algorithm explainer. It is dense, with two long sentences, but almost every phrase adds relevant scope or previews returned content.

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, a read-only annotation, and no output schema, the description carries the necessary burden of explaining what the tool returns and when to use it. It explicitly lists the returned material and links the tool to simulate_k2_session, leaving no important invocation ambiguity.

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?

There are zero parameters, so parameter semantics are not a meaningful gap. The schema is empty and fully described, and the description appropriately avoids inventing parameter guidance for a no-argument 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?

The description immediately identifies the resource and action: it explains/describes the K2 spaced-repetition engine and enumerates what the explanation returns. It also distinguishes itself from the sibling simulate_k2_session by positioning itself as prerequisite reading rather than execution.

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?

It gives explicit usage context: 'Read this before simulate_k2_session.' That makes the relationship to the key sibling clear, though it does not state when this tool should be used instead of other documentation-style siblings or whether it is ever unnecessary.

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