check_vpn_accessibility

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

No annotations are provided, so the description carries full burden. It does disclose a meaningful behavioral fact — results come from Voidly probe-node tests — which tells the agent the data source and its test-based nature. It still omits data freshness, coverage limits, auth requirements, and result shape, so it only partially discharges the obligation.

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 tight sentences: purpose first, then an illustrative example that earns its place by disambiguating the direction of the lookup. No filler or restatement of the title.

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 and no annotations, so the description should ideally convey the shape of the answer. The Iran example hints at a per-country connectivity verdict, which partially covers this, but details like result granularity or filtering behavior are not addressed.

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%, so both parameters (provider list, ISO country code) are already fully documented in the schema. The description adds no syntax or format detail beyond that, making the baseline 3 the correct call.

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 specific verb and resource ('Check VPN accessibility from different countries') and reinforces it with a concrete example question. It is clearly distinguishable from siblings like check_domain_blocked or check_service_accessibility by resource, but never names or contrasts them 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 example question ('Can users in Iran connect to VPNs?') implies when this tool is useful, so usage is inferable. However, there is no explicit statement of when to use it versus alternatives, and no mention of prerequisites, so guidance is only implicit.

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