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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the non-mutating, network-touching profile is covered structurally. The description adds that it 'explains every failure', which is useful output behavior, but says nothing about auth, rate limits, or what a passing result looks like.

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 first covers what is validated and the failure-reporting behavior, the second covers when to use it. The accepted-input list is front-loaded 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?

For a single-parameter, read-only validation tool with annotations covering the safety profile, this is nearly complete; it even notes that failures are explained. It stops just short of describing result shape or any limits on remote fetching that openWorldHint implies.

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% and the single url parameter is already documented as 'Card, origin, feed or policy URL (https)'. The description only restates those same accepted input kinds, adding no format or routing detail 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?

The description states a specific verb (checks/validates) plus the exact resources covered: Agent Card, agent origin, feed, and group policy, with the standard named (RSS-A spec). It clearly contrasts with the read siblings by being a verification action, though it never names rssa_read_feed or rssa_read_group explicitly.

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 second sentence gives an explicit use case: check your own agent or a peer before trusting it. That is real when-to-use guidance, but there are no exclusions or stated alternatives to the sibling read tools.

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