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

Annotations already declare readOnlyHint and openWorldHint=false, so the safety profile is covered. The description adds scope detail the annotations cannot: it discloses exactly which content is returned and, importantly, that band summaries only span 5–8, which prevents the agent from promising Band 9 or Band 4 guidance.

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 front-loaded sentence enumerating the returned content, followed by a short use-case clause. Every element earns its place; no rephrasing of the title or 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?

For a static, parameterless reference lookup with no output schema, the description is nearly sufficient: content scope and band range are stated. It could go one step further and say whether the result is structured/markdown text and that criteria are criterion-by-criterion, but nothing blocks a correct call.

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; baseline is 4. No misleading parameter claims are made.

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 ('Get the four IELTS Writing assessment criteria') and enumerates the exact payload: criteria, Task 1/Task 2 differences, and Band 5–8 summaries. This is clearly distinguishable from the sibling sample/cue-card tools, which return user content rather than reference material.

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 concrete usage context ('essay self-review, feedback prompts and study plans'), which tells the agent when this reference lookup is worth calling. It does not name alternatives or exclusions (e.g., telling the agent to prefer get_writing_sample when a concrete example is needed), so it falls short of a 5.

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