zabbix_unreachable

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

Annotations already declare read-only, idempotent, non-destructive, open-world behavior, so the safety profile is covered. The description adds real value beyond that: availability is derived from the interface rather than host.available (removed in 5.4), and results exclude hosts with silent items. It does not describe the result shape or ordering, which keeps it short of a 5.

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?

Front-loaded with the core purpose in one line, then usage, then exclusions. Each sentence is doing work, though the 'code still reading it sees nothing at all' remark is aimed more at maintainers than at the calling agent and is slightly surplus.

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 single-filter list tool with no output schema, the description covers purpose, scope, the availability semantics, and sibling routing. It stops short of describing what each returned row contains (host, interface type, error), a minor gap given no output schema exists.

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?

Only one optional parameter (limit) and schema description coverage is 100%, including the truncation-reporting behavior, so the schema carries the full burden. The description adds no parameter-level detail, which is the expected baseline 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?

The opening sentence gives a precise verb and resource ('List monitored hosts Zabbix currently cannot poll') and the scope is unambiguous. The third paragraph further distinguishes it from zabbix_host_investigate and zabbix_metrics_latest by naming the condition under which those siblings apply instead.

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?

Explicitly states when to use it ('which hosts Zabbix cannot poll, or which agent, SNMP, IPMI or JMX interfaces are down') and, critically, when not to ('a host whose interface is up but whose items went silent is not listed here'), routing that case to zabbix_host_investigate.

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