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

With no annotations, the description carries the burden. It discloses what the tool returns (list of readings, their measurement purpose, and key requirements) and implies it's a read-only operation. While it doesn't cover pagination or response size, the described behavior is clear enough for a simple catalog 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?

Two concise sentences front-load the core function ('List every reading') and immediately follow with what each entry includes and a usage hint. No wasted words and all information is relevant.

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?

Despite having no output schema, the description covers what the tool does, what information it provides (measurement and key requirement), and when to use it. For a listing/discovery tool, this is complete and actionable.

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, and the baseline for zero-parameter tools is 4. The description adds no parameter-specific details because none exist; it sufficiently explains what the output will contain instead.

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 states the tool lists every available reading, including what each measures and key requirements. This is a specific verb+resource (list + readings) and distinctly positions the tool as a catalog/discovery mechanism among the many specialized sibling tools.

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 explicitly says to call this tool first when unsure which tool answers a question, providing a clear when-to-use signal. It doesn't mention exclusions or name specific alternatives, but the context strongly implies it serves as a triage tool.

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