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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description adds genuine behavioral context beyond that: it discloses what the practice surface contains (scrollable lane, guide, stroke playback, trace pad, score), which tells the agent what to expect from invoking it. No mention of what happens if both text and preset are supplied.

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?

Two sentences, front-loaded with the action and followed by the input modes; no filler. The UI inventory in the first sentence is dense but each element informs the agent about the returned surface.

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 5 optional parameters, full schema coverage and an output schema, the description is close to sufficient. Minor gaps remain around precedence between text and preset and around how guide/style/alphabet combine, but the core call path is clear.

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 a 3 is the baseline, but the description earns a point by expanding 'practice preset id' into concrete examples (everyday words, loops and joins, numbers, lesson exercise, kids size set) that the schema does not provide. It does not explain how text and preset interact when both are given.

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: 'Opens the one-lane handwriting practice' with the text lane, guide, stroke playback, trace pad and score. The adjective 'one-lane' implicitly separates it from the worksheet sibling, but no sibling is named explicitly, so differentiation is left to inference.

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 rather than stated: 'one-lane' plus 'custom text or a practice preset id' suggests single-user interactive practice rather than a printable worksheet, but the description never says when to pick this over make_worksheet or show_letter, and gives no exclusions or prerequisites.

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