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

Annotations already carry readOnlyHint=true, idempotentHint=true, and openWorldHint=false, so safety and idempotence are covered elsewhere. The description adds value the annotations do not: it is free and requires no API key, which is meaningful auth information for an agent deciding whether it can call it. It also briefly states what comes back ('ok and version'), though it omits what happens on failure.

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?

Three terse fragments, front-loaded with the operation type, then the return shape, then the access conditions. No filler, no redundancy, nothing that could be cut without losing information.

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 zero-parameter, no-output-schema liveness probe with rich annotations, the description supplies everything an agent needs to call it correctly: what it does, what it returns, and that no auth is required. The only missing piece is failure/error behavior (e.g., whether it throws or returns a non-ok status), a minor gap for this tool class.

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, so there is nothing for the description to disambiguate and the baseline is 4. No misleading parameter hints are present, and the schema is consistent with the description.

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 a specific operation ('Liveness check') and even discloses the return payload ('ok and version'), which is more than a restatement of the name. Sibling tools are all in unrelated domains (cross_border_check, money_fact, pricing_list, scheme_lookup), so no differentiation is required. It stops short of a full sentence identifying the target resource, relying on the title for that.

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?

'Free, no key' implies the tool is safe to call without credentials and at no cost, which is indirect guidance that it can be used freely as a probe. However, it never states when to use this versus other tools, nor any preconditions or failure semantics. Usage is implied rather than stated.

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