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

Goes well beyond the annotations: it discloses that it runs as a tracked operation, that node pools follow provider-specific upgrade behaviour (i.e., are not upgraded directly here), and critically that the action is not reversible because managed control planes cannot be downgraded. That irreversibility detail is exactly the behavioral context the destructiveHint alone cannot convey.

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-loads the action and target, then layers prerequisite, runtime behavior, and irreversibility warning in compact sentences. Every sentence carries actionable information with no 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?

For a destructive mutation with no output schema, the description covers the prerequisite lookup, the preconditions, the tracked-operation semantics, and the irreversibility risk. An agent has everything needed to call it safely without additional context.

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 cluster_id, cluster_name, and target_version are already documented in the schema. The description reinforces that target_version is an available upgrade and points to where candidates come from, but adds no syntax or format detail beyond the schema. Baseline 3 is appropriate.

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?

Specific verb (Upgrade) plus precise resource scope (managed Kubernetes cluster's control-plane version), which separates it from node-pool and agent upgrade siblings. It does not explicitly name which sibling to prefer over choices like upgrade_cluster or roll_cluster_to_version, but the resource scope is unambiguous.

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?

Gives a concrete prerequisite workflow ('Use list_managed_k8s_options with the cluster target first') and states preconditions (cluster must have finished provisioning, no in-progress operations). It lacks explicit exclusion routing against sibling upgrade tools, so it lands just below the top tier.

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