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

Annotations already declare the safety profile (readOnlyHint=false, idempotentHint=false, destructiveHint=false), so the description only needs to add context. It adds the 'once per session' cadence, but leaves unexplained why a tool that merely 'returns two test pictures' is marked non-read-only and non-idempotent – the agent cannot tell whether a call records session state or what happens on a repeat call.

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?

Three short lines, front-loaded with what it returns and followed by when to use it. The 'Example: {}' line is near-filler for a zero-parameter tool but is not harmful.

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 correctly states the return value (two test pictures). But it omits the confirm_vision_probe handoff and what the agent should conclude or do based on the images, leaving the workflow half-specified for a probe tool whose whole purpose is gating later calls.

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?

Zero parameters, so the baseline is 4; the description reinforces this with 'Example: {}', making clear no arguments are needed. Nothing further is required.

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 concrete verb and outcome: 'Returns two test pictures to check you can read images on this connection.' No sibling does anything comparable, so it is distinguishable, though it never frames itself as part of the vision-probe flow alongside confirm_vision_probe.

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?

'Use when: once per session, before picture tools' gives real timing guidance, which is more than most tools offer. However, it omits the obvious follow-up sibling confirm_vision_probe and gives no when-not condition (e.g. what to do if the images cannot be read).

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