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

Annotations already declare readOnlyHint=true, destructiveHint=false, so safety is covered; the description adds that this is a timed TCP connect used as a triage step. It does not mention rate limits, what a failure/timeout yields, or that the target is arbitrary external infrastructure (notably at odds with openWorldHint=false, though the description itself doesn't assert closed-world).

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: the mechanism comes first, the diagnostic purpose second. No filler and no 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?

With an output schema present, the definition needn't describe return values, and annotations cover the safety profile. What's left thin is parameter-level guidance for timeoutMs and the openWorldHint inconsistency, so it's strong but not airtight.

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 coverage is 75% with host, port, and context_id documented in the schema; only timeoutMs lacks a schema description. The description mentions a timeout generically but doesn't tie it to the timeoutMs parameter, its default of 15000, or its 1–60s bounds, so it adds little beyond the schema.

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?

Uses a concrete verb+resource: checking host:port reachability via a TCP connect with timeout. It implicitly distinguishes itself from dns_lookup/http_check by framing the result as separating DNS failures from network/firewall issues, though it never names a sibling outright.

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 to distinguish DNS failures from network/firewall issues" gives a clear diagnostic context for selecting this tool over a DNS or HTTP check. It lacks explicit when-not conditions or a named alternative, so it stops 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.