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

Annotations already declare readOnlyHint=true and the description's 'Read-only' merely repeats that, earning no credit. However, with no output schema the description usefully discloses the returned fields (name, value, description, timestamps) and the non-obvious semantic that these values override organisation variables at interpolation time, which is real behavioral context.

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 sentences, both front-loaded with the highest-value information: what is listed first, then the override semantics and return shape. No filler or restated boilerplate.

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 tool with annotation-covered safety and no output schema, the description supplies the semantic meaning, the override relationship, and the return fields. Nothing needed to call it correctly 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%, so the single cluster_id parameter is fully documented in the schema (including the pointer to list_clusters for id discovery). The description adds only the notion of 'current cluster' scoping and no format or constraint detail, so baseline 3 applies.

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 ('List the current cluster's variables') and immediately qualifies what those variables are: plain-text config values interpolated by stack definitions. The override relationship with organisation variables implicitly distinguishes it from the sibling list_organisation_variables, so an agent can route correctly without opening either 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?

Usage is implied by the scoping language ('current cluster's variables', 'overriding organisation variables of the same name') but there is no explicit when-to-use versus list_organisation_variables, and no stated prerequisite beyond the cluster_id parameter. Adequate context, no exclusions.

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