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

Annotations already declare readOnly/idempotent/non-destructive, so the description adds value with the auth note ('No account or token needed') and the qualifier 'when known,' which signals that the drafts field may be absent. It does not discuss failure behavior for unknown RFC numbers, which is the main remaining gap.

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 labeled lines, front-loaded with the return payload, then usage, then auth note and example. Every sentence carries information and nothing is padded.

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 covering return structure and annotations covering safety, the description supplies everything needed to decide and invoke: purpose, timing, auth, and a call example. Only edge-case behavior (invalid or nonexistent RFC numbers) is unaddressed.

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 100% — the rfc parameter already documents accepted forms (9110 or 'RFC 9110') with a regex pattern. The description's example arguments restate what the schema already conveys, adding almost no new 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?

States a specific verb (Return) and precisely enumerates the resource: status, obsoletes/obsoleted-by and updates/updated-by links, errata by category, and active drafts. This is far more specific than the title and makes the scope unambiguous; no sibling tool covers RFC status, so confusion risk is low.

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 'When to use' line gives a concrete decision rule: check before relying on an RFC, to see whether it is current or whether errata alter the cited text. It does not name an alternative or state exclusions, but the sibling list contains no comparable tool, so the guidance is sufficient.

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