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

Annotations already declare readOnlyHint and openWorldHint, and the description is consistent with both while adding real context: it makes clear live outbound calls are made to the agent's https endpoints and that domain listings and reputation concentration are evaluated. 'Nothing is paid or written' is a useful boundary statement. It stops short of stating rate limits, behavior for an unknown id, or whether failures are surfaced as errors versus result flags.

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?

Everything is front-loaded into a single dense sentence that leads with 'Free: check…' and then the scope. Every clause earns its place by naming a distinct check, but the run-on structure with four 'whether…' clauses is harder to scan than a short bulleted breakdown would be.

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 no output schema, the description carries the burden of conveying what comes back, and listing each evaluated dimension effectively implies per-check pass/fail results. The remaining gap is the concrete result shape and what happens for a nonexistent or unregistered id, which an agent would want before calling.

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% — agent_id is already documented as 'The agent's id on Base' with bounds. The description adds only the locator context that the id lives in the Identity Registry, which is a marginal clarification rather than new semantics. Baseline 3 is appropriate when the schema does the heavy lifting.

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?

It states a specific verb and resource — check an ERC-8004 agent on Base by its id in the Identity Registry — and then enumerates the exact facets verified (registration file validity, https endpoint liveness, domain listing, x402/A2A lint, reputation concentration). That is far more specific than a generic 'get agent card'. It does not, however, distinguish itself from overlapping siblings such as lint_listing, certify_offer, or check_offer, which also involve offer/card validation, so it falls short of 5.

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 'Free: … from outside' framing and 'Nothing is paid or written' imply this is the read-only inspection path, and the enumerated checks imply the use case (vetting an agent before interacting). But there is no explicit when-to-use statement, no exclusion, and no pointer to the sibling tools that cover the paid or write-side flows, leaving the agent to infer routing.

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