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

Annotations already declare readOnlyHint=true, destructiveHint=false, openWorldHint=false, so the safety profile is covered; the description still adds real value: values are fetched live from the hosting system, returned values are exactly the accepted inputs of switch_php_version, unreadable values are not 'none', and limits derive from the tariff. That is behavioral context an agent cannot get from the annotations or 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?

The core purpose and the sibling routing come first, then the fallback warning and field semantics. It is somewhat long at seven sentences, and the closing note on upload_max_filesize vs post_max_size sits at the tail where it is easy to skim past, but no sentence is pure filler.

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 carries the burden of explaining returns and does so: current version, selectable versions, tariff-derived limits, effective upload limit, and how to interpret an unreadable value. It stops short of describing the actual response shape or whether selectable versions are ordered, a minor remaining gap for a single-parameter 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 coverage is 100% with one required 'domain' parameter, so the baseline is 3. The description only reinforces the scoping constraint ('EINE Domain', i.e. one domain per call, not a batch) and adds no format or validation detail beyond the schema's example.

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 and resource ('liest für EINE Domain die eingestellte PHP-Version und die Versionen, die auf ihrem Server wählbar sind') and immediately names the sibling 'switch_php_version' as its write counterpart, plus the user question it answers. An agent can distinguish it from all 100+ siblings without opening the 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?

Explicitly frames the tool as the read counterpart to switch_php_version and the correct answer path for 'Welche PHP-Versionen gibt es?'. It also gives an exclusion-style rule: if a value is reported unreadable, do not guess and do not trigger a switch to probe — which prevents a concrete misuse of the sibling.

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