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

readOnlyHint=true already tells the agent this is a safe read, so the bar is lower. The description adds the upstream endpoint mapping, which is mildly useful, but says nothing about error behavior (404), pagination, or response shape.

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 very short sentences with no filler, and the core action is front-loaded. It is terse but every clause carries 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 single-parameter read with full schema coverage and a readOnlyHint, the description is adequate. With no output schema, a brief note on what is returned or on not-found behavior would round it out, but nothing essential is missing.

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, so the description cannot add much. It confirms the id-based lookup but provides no format or range nuance. Baseline 3.

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 (Fetch) and scope (a single resource by id), and the endpoint line 'GET /volumes/{id}' pins down the resource even though the prose itself says only 'resource'. An agent can distinguish this from the list_volumes sibling via the 'single' vs. list pattern.

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?

Usage is implied — fetch one by id — but the description never says when to prefer this over hetzner_list_volumes or what happens if the id does not exist. No exclusions or prerequisites are stated.

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