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

Annotations already declare readOnlyHint, openWorldHint, idempotentHint as true, and destructiveHint as false, so the safety profile is well-covered. The description adds valuable behavioral context by mentioning 'modern transport capability advertisement' and the RFC standard. It does not contradict annotations, and complements them with the domain-specific purpose. One could argue for a 5, but the description does not detail caching behavior beyond what the 'force_refresh' parameter implies.

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?

The description is two sentences, front-loaded with the core purpose, and every sentence adds value. The first sentence defines the tool's function with RFC specificity, and the second provides organizational context. No wasted words.

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?

Given the tool has a clear input schema (100% coverage), comprehensive annotations, an output schema, and a straightforward domain-checking purpose, the description is complete. It does not need to explain return values because the output schema exists. The RFC reference and audit context provide sufficient richness for the agent to use the tool correctly alongside many sibling tools.

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 100%, so the baseline is 3. The description adds marginal value by referencing RFC 9460 which implies the validation standard, and mentions 'part of the scan_domain audit' which contextually ties the parameters (domain, format, force_refresh) to a broader audit workflow. However, it does not elaborate on the 'format' parameter beyond the schema, nor explain how 'force_refresh' interacts with caching. Still, the high schema coverage means the schema carries the bulk of the meaning.

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 clearly states the tool validates HTTPS/SVCB records per RFC 9460 for modern transport capability advertisement, using a specific verb ('validate') and resource ('HTTPS/SVCB records'). It also identifies the tool as part of the 'scan_domain audit', which helps distinguish it from the many sibling tools like check_caa, check_dane, and others that operate in the same domain audit context.

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 description mentions this is part of the 'scan_domain audit', giving some context, but does not explicitly say when to use this tool vs alternatives like check_dane_https, check_http_security, or check_ssl. There is no guidance on when not to use it or what prerequisites are needed. The agent must infer usage from the RFC 9460 reference and the tool name.

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