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

Annotations already declare readOnlyHint=false, idempotentHint=false and destructiveHint=true, so the write/non-idempotent profile is covered structurally. The description adds genuinely new behavioral context beyond that: "The cluster will begin provisioning immediately after creation," i.e. no dry-run or confirmation step and side effects start at once. It stops short of covering cost implications or how the resource is later torn down, so it is not quite 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?

Five dense sentences with no filler, ordered from what the tool does to prerequisites to optional behavior to immediate side effects to prerequisite-lookup tools. For a 21-parameter tool this is an appropriately sized, front-loaded introduction.

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 return-value burden and does not describe the create result (though the schema notes the result names auto-picked server types). It otherwise covers prerequisites, optional modes, and immediate provisioning for a large, complex creation tool. The main remaining gap is the absence of any lifecycle/cost framing (e.g. cleanup via delete_cluster, billing impact).

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%, so the baseline is 3 and the schema already documents defaults, enums and UUID sources. The description still adds cross-parameter meaning the schema only implies per-field: node_groups replacing worker_count/worker_server_type, GitOps defaulting to GitHub unless gitops_provider is 'bitbucket_cloud', and the guidance to omit server types so the platform selects location-provisionable ones. That is a modest but real increment over the schema.

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 opens with a specific verb+resource+provider ("Create and provision a new Kubernetes cluster on Hetzner Cloud"), which cleanly separates it from the many sibling cluster-creation tools (create_aws_cluster, create_digitalocean_cluster, create_proxmox_cluster, create_managed_cluster). It also enumerates the distinguishing capabilities (GitOps, heterogeneous node groups) that an agent needs to match the request to this tool.

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?

It states the prerequisites explicitly (Hetzner API credential, at least one SSH key credential, a datacenter location) and then routes the agent to the exact prerequisite-lookup siblings: list_provider_credentials, list_instance_types, list_gitops_credentials and list_gitops_repositories, each with the reason to call it. It even flags a caveat about list_instance_types not showing per-location stock, which is real when-to-use guidance.

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