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

With no annotations, the description carries the full burden and does disclose that this is a canonical single-record pointer (not a list) and what fields constitute it, implying a read-only lookup. It omits any mention of auth needs, caching/freshness semantics beyond 'freshest', or failure modes, keeping it out of the top band.

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 sentences, zero filler. The identity/scope statement is front-loaded and the usage instruction follows immediately, with the returned-field list embedded in the first sentence where it is most useful.

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?

There is no output schema, so the description must convey return content, and it does by naming the five fields. It does not explain field formats (date encoding, hash algorithm, meaning of 'previous revision' on a first revision), leaving a small gap for a zero-param lookup 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?

The tool takes zero parameters, which is the baseline-4 case; there is nothing for the description to disambiguate. The description's field list describes the return payload rather than input, which is appropriate here.

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?

Names a specific verb+resource ('Return the single canonical "what is current" pointer') and enumerates exactly what comes back: snapshot date, hash, signed_at, pubkey_id, previous revision. An agent can distinguish this from verify_snapshot or get_sector without opening any schema.

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?

Gives an explicit sequencing rule: use this before querying a specific snapshot date to know what's freshest. That is actionable context for tool selection. It stops short of naming sibling alternatives or stating when not to use it, so it is not a full 5.

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