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

Annotations already establish this as a read-only, idempotent, closed-world, non-destructive operation, so the safety profile is covered. The description adds one genuine behavioral fact beyond that: presence may be absent or expired, meaning the caller must handle a no-result case. It says nothing about the returned payload's shape or freshness semantics beyond 'right now'.

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?

A single sentence with no filler, and the temporal qualifier 'right now' is placed early. It is a noun phrase rather than an action statement, which slightly weakens front-loading of the verb, but nothing is wasted.

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 should convey what a caller receives, and it only implies it loosely — it states the expiry condition but not what the presence record contains or what an empty result looks like. Combined with the missing get-vs-lookup differentiation, it is adequate but leaves real gaps for this simple, well-annotated read tool.

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 parameter 'key' is fully documented in the schema (Ed25519 public key, 32 bytes, base64url, with a regex pattern), so the schema carries the load. The description adds no parameter-level detail, which is the baseline 3 case for a fully documented single parameter.

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 names the resource (a key holder's presence) and scopes it precisely in time ('right now') and state ('published, not expired'), so an agent knows this returns current reachability rather than historical data. It does not, however, distinguish itself from the sibling aamio_presence_lookup, leaving the get-vs-lookup split to inference.

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?

There is no when-to-use guidance, no statement of prerequisites, and no routing to alternatives such as aamio_presence_lookup or aamio_presence_set. The agent must guess which presence tool to call from names alone.

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