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

The readOnlyHint=true annotation already establishes this is a safe, non-mutating read, so the description's burden is lighter. It adds the underlying endpoint mapping (GET /primary_ips/{id}), which is mildly useful context, but says nothing about error behavior for an unknown id or what fields come back — and there is no output schema to cover that.

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 short sentences, front-loaded with the action, with no filler. It is efficient, though the first sentence is boilerplate that could have carried more specificity at the same length.

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 simple single-id read with full schema coverage this is minimally adequate, but with no output schema the description could have sketched the returned primary IP fields or noted behavior for a missing id. The endpoint mapping is the only extra context supplied.

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 description coverage is 100% and the single id parameter is fully documented in the schema ("The resource's numeric id."), so the baseline of 3 applies. The description adds no format, range, or sourcing detail beyond what the schema already states.

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 says "Fetch a single resource by id" — a generic template phrase that never names the resource as a primary IP; only the HTTP path suffix "primary_ips/{id}" pins it down. It implicitly contrasts with the sibling hetzner_list_primary_ips (single vs. list) but never states that distinction.

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?

No when-to-use guidance is given: nothing tells the agent to pick this over hetzner_list_primary_ips when it already has an id, nor that it is a point lookup rather than a search. The only usable cue is the name and endpoint.

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