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

Annotations already declare readOnlyHint, openWorldHint, idempotentHint and destructiveHint=false, so the safety profile is covered. The description does add useful behavior context by disclosing that it performs an actual live QUIC handshake probe (i.e., outbound network activity, possible latency or firewall blocking), but it says nothing about timeouts, failure modes, or what a negative result means.

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?

A single front-loaded sentence with the capability stated first and the mechanism list in a parenthetical; there is no filler. Slightly denser than needed but every clause carries information.

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?

For a one-parameter read-only probe this is nearly sufficient, but with no output schema the description never indicates what the result looks like (e.g., per-protocol supported/not-supported verdicts) or how inconclusive results are reported. Minor gaps remain for a simple tool.

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?

With a single parameter at 100% schema description coverage, the schema already explains that 'host' is a public host name such as example.com. The description adds no further meaning (e.g., no-URL-scheme, no-port, no-IP constraints), so the baseline of 3 applies.

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 ('checks') and a precise resource ('whether a site supports HTTP/2 and HTTP/3'), then names the concrete mechanisms (ALPN, Alt-Svc, QUIC handshake). This clearly separates it from sibling checks like http_headers_check or ssl_check, though it never names an alternative 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?

Usage is only implied: an agent can infer this is the tool for protocol-version/QUIC support questions. There is no explicit when-to-use, when-not-to-use, or routing guidance versus http_headers_check or ssl_check, which also touch TLS/HTTP behavior.

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