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

Annotations already declare readOnly, idempotent, non-destructive and closed-world behavior, so the safety profile is covered. The description adds genuinely new behavioral context with 'step-by-step guided check — no automatic probing', telling the agent this tool guides the user rather than issuing network requests itself. This is useful and non-redundant, though it could say more about what the guided check entails.

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 sentences, both earning their place: the first front-loads the usage trigger and the second discloses the non-probing behavior. There is no filler or repetition.

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?

An output schema exists, so return values need not be described, and with zero parameters the definition only needs purpose, trigger, and behavior — all present. It is slightly incomplete in omitting what the guided check steps involve and any alternative tools, but it is adequate for a parameterless, read-only diagnostic.

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 takes zero parameters and schema coverage is 100%, so there is nothing for the description to compensate for. Baseline 4 applies; no parameter explanation is needed or expected.

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 names the resource (captive portal / login page) and the action (step-by-step guided check), and the 'no automatic probing' clause implicitly separates it from probing siblings like run_speed_test, measure_latency, and get_public_ip. It is clear, though the core verb is softer than a crisp 'detect' statement and no sibling is named explicitly.

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 trigger condition is stated concretely: use when the user is on hotel/airport/cafe Wi-Fi and suspects a login page is blocking them. That is a clear context for use. It does not name any alternative tool or state when not to use it, so it falls short of a 5.

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