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

Annotations already cover safety (readOnly, idempotent, non-destructive), so the bar is lower, and the description adds real behavioral content: the official .25/.75 rounding rule and the caveat that the Task-based Writing estimate is approximate. Flagging the estimate's lower confidence is genuinely useful disclosure beyond the structured fields.

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 dense sentences with no filler; the core calculation and its rounding rule come first, and the optional Task-based path follows. Every clause carries information.

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?

There is no output schema, so the description should convey what comes back; it implies a resulting band but does not explicitly state the output shape or whether the estimated Writing band is returned separately. Given the tool's simplicity and the annotations, this is a minor gap.

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%, so the description must carry parameter meaning, and it does: it maps the four band inputs and explains that writingTask1/writingTask2 are an optional alternative path where Task 2 counts double. It aligns with the schema's required list by saying the Task inputs are optional, though it does not restate the 0-9 / 0.5-step constraints (which the schema encodes).

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?

Starts with a specific verb and resource ('Calculate the overall IELTS band') and enumerates the exact inputs (Listening, Reading, Writing, Speaking). It is unambiguous and cannot be confused with any sibling tool such as analyze_writing or search_vocabulary.

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 description implies usage by explaining the required four-band input and the optional Task 1/Task 2 mode, so an agent can infer when it applies. However, it never states when to use this instead of siblings or any preconditions, leaving routing to inference.

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