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

With no annotations provided, the description carries the full behavioral burden and does so well: it states 'Read-only, no probing,' identifies the file as public and owner-published, explains fallback from /.well-known/security.txt to /security.txt, and lists the returned fields including conformance warnings. This is far beyond what the schema or annotations supply.

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 front-loaded with the core action and then densely lists exactly what is returned and how the fetch behaves. Every clause earns its place, and the final sentence 'Read-only, no probing.' efficiently reinforces the safety profile.

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?

Despite having no output schema and no annotations, the description fully covers the retrieval behavior, fallback logic, return contents, and relationship to the sibling abuse_contact tool. An agent has everything needed to select and invoke it correctly.

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% and the single domain parameter is already documented as 'Domain or URL, e.g. example.com.' The description adds context about what file is fetched from that domain but does not add parameter-specific semantics such as accepted URL schemes or normalization rules, 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?

The description uses a specific verb ('Fetch') and resource ('site's vulnerability-disclosure file (RFC 9116)') and names the file paths, so an agent can immediately tell it apart from siblings like abuse_contact and disclosure_contacts. It also clarifies the fallback location and the exact contents returned.

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 explicitly distinguishes this tool from abuse_contact by calling it a complement to 'the RIR's registered mailbox' and framing it as 'the owner's own disclosure channel.' It gives clear context for when to reach for it, but does not include explicit when-not conditions or a full routing rule.

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