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

Annotations already declare readOnlyHint/idempotentHint and non-destructive, but the description adds meaningful context beyond them: the server holds no key and does not act as a session key or guardian, which clarifies the non-custodial trust posture. It stops short of disclosing rate limits or failure behavior.

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 compact sentences that are front-loaded with the resource and its contents. The 'Read-only' clause partially echoes the readOnlyHint annotation, though the key/guardian specifics that follow give it independent value.

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 present, return values needn't be explained, and the description still characterizes the returned data (session keys, guardian thresholds). Safety posture is covered by annotations plus the non-custodial note, so nothing essential for correct invocation is missing.

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%, so the schema already documents the single address parameter, including its aether1... format. The description only restates that the address is required, adding no syntax or format detail beyond the schema. Baseline 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?

States a specific verb ('See') and a precisely scoped resource ('pluggable authenticators (x/accountauth) an address has registered'), then enumerates the content: session keys and guardian thresholds. No sibling tool overlaps this operation, so an agent can select it unambiguously.

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 narrow scope (per-address authenticator lookup) implies when to call it, and the required address is called out. However, it names no alternatives or when-not conditions, and gives no guidance on what to do with an unregistered address.

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