Read the display

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

Annotations already declare readOnlyHint=true, so the safety profile is covered. The description adds valuable behavior beyond annotations by explaining the returned display contents, the SI-base-unit meaning of value, the display text field, and the METER_BUSY error condition.

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 dense but front-loaded around the snapshot concept and then systematically lists returned components. The parenthetical enumerations are somewhat long, but every clause earns its place by clarifying return content or error behavior.

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 no output schema, the description carries the burden of explaining return values, and it does so well by naming the display fields, units, and METER_BUSY state. It is not fully complete on sibling selection or the max_wall parameter, but the core read behavior is sufficiently covered.

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 100%, and the only parameter, max_wall, is fully documented in the input schema including its default, bounds, and timeout behavior. The description adds no additional parameter meaning beyond what the schema already provides, so the baseline of 3 is appropriate.

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 resource and scope: 'One snapshot of the meter display,' then enumerates what the snapshot includes. It is specific enough for an agent to understand the tool, but it does not explicitly contrast itself with siblings such as live or status.

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 phrase 'One snapshot' implies this is for a single sample rather than continuous streaming, which is useful context against the live sibling. However, the description never explicitly states when to use this tool instead of live, status, or memory, nor does it name alternatives.

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