check_proxy

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

Annotations already declare readOnlyHint=true, openWorldHint=true, destructiveHint=false, so the safety profile is covered. The description adds real value beyond that: it discloses that no traffic traverses the tunnel, that the return includes gateway status, exit IP (conditionally), and connection duration, and warns that a 407 may indicate a bad parameter rather than bad credentials. That last point is a non-obvious behavioral caveat.

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 sentences, front-loaded with the action, followed by the traffic/return behavior and the diagnostic caveat. 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-value detail is not strictly required, and the description still helpfully previews what comes back. The significant gap is the seven completely undocumented optional parameters for a tool that is parameter-sensitive (per the 407 note). An agent could call it, but not confidently steer it.

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 0% across 7 parameters (isp, ttl, city, filter, region, country, session_id), so the description carries the full burden and largely fails. The only nod to parameters is 'A 407 can mean a wrong parameter value,' which hints they affect routing/auth but explains none of their meaning, formats, or interactions.

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: 'Open one connection through the proxy and report the result.' Combined with the second sentence ('Sends no traffic through the tunnel'), the scope is clear and distinguishable from sibling tools like proxy_url or traffic_stats. It doesn't explicitly name a sibling to differentiate, which keeps it out of the top band.

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 line 'Sends no traffic through the tunnel' implies this is a lightweight connectivity/diagnostic check rather than a data-moving call, which is useful implied usage. However, there is no explicit statement of when to prefer this over proxy_url, list_locations, or account_status, and no exclusions.

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