apiinfo_version

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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered. The description adds genuinely useful context beyond them: the returned value is the frontend version (not, say, the server daemon version), which matters for version-gating, plus the relationship to health_check. It does not mention auth requirements or the raw_json policy caveat, but those live in the schema.

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 short sentences, front-loaded with what is returned, then usage, then the sibling distinction. Every sentence carries information and nothing is padded.

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 parameterless-by-domain, read-only lookup with an output schema and readOnlyHint annotation, the description covers purpose, usage and return semantics adequately. The only gap is the slightly misleading 'takes no parameters' phrasing, which ignores the server/raw_json inputs the caller may still need to set.

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%, so the schema already documents 'server' and 'raw_json' in detail, including the raw_json PolicyError and prompt-injection warning. The description adds nothing about either parameter and in fact says 'Takes no parameters', which is imprecise given two operational parameters exist. Baseline 3 applies when the schema does all the work.

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+resource ('Return the version of the Zabbix API'), disambiguates which version (the frontend version) and gives a concrete example format ('7.4.14'). It also explicitly separates itself from the sibling health_check, so an agent can tell the two apart without opening either 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?

'Use it to pick version-specific tools and parameters' gives a clear motivating context, and the health_check clause names an alternative along with the condition that distinguishes it (per-server vs. this server). No explicit when-not or multi-server routing rule beyond that implication, so it falls short of a full 5.

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