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

With no annotations provided, the description carries the full burden of behavioral disclosure. It states that the tool returns a 'plain-text explanation' and outlines the exact topics covered, which effectively communicates read-only behavior and output content. It does not mention potential limitations like language or formatting, but for this simple methodology tool, the disclosure is strong.

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 compact yet information-dense, using a single sentence to enumerate the key content and a second sentence to provide usage context. Every clause earns its place, and the main purpose is front-loaded.

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?

Given the tool's simplicity (no parameters, no output schema), the description fully covers what the tool does, what it returns, and when to use it. The list of returned content is sufficiently detailed, making the tool self-explanatory even without additional structured information.

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 has zero parameters, so the baseline is 4. The description needs to add no parameter meaning, and indeed none is needed. The schema is empty with 100% coverage, so there is nothing further to clarify.

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 clearly identifies the tool as providing an authoritative plain-text explanation of the ieUnit's definition and calculation, listing specific content areas (geometric mean formula, fixed base date, data sources, governance rules, and what it is NOT). This distinguishes it from sibling tools like ieunit_convert or ieunit_history, which focus on calculations or historical data.

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 gives explicit usage guidance: 'Call this before describing or characterising the ieUnit to a user.' This makes the intended context clear. However, it does not explicitly mention when not to use it or name alternative tools for other tasks, so it stops short of full when/when-not guidance.

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