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

Annotations already cover the read-only safety profile, yet the description adds genuinely useful behavior: the required variables.read permission, that secret-marked variables are returned with a null value, and that platform-owned settings are omitted entirely. These are non-obvious output semantics an agent could not derive from readOnlyHint alone.

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-loaded with the core purpose, then layers return fields, secret handling, exclusion, and permission. Dense but no sentence is filler; the opening clause is slightly overloaded with the interpolation-syntax detail.

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 so: it enumerates returned fields (name, value, description, is_secret, timestamps) and explains the secret-null behavior and platform-owned exclusion. 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?

Zero parameters, so per the rubric the baseline is 4. There is nothing for the description to clarify beyond confirming that the call takes no arguments, which the empty schema already conveys.

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 (list) and resource (organisation's variables), then defines what those variables are: plain-text config values interpolated via ${{ ankra.variables.* }}. The phrase 'shared by every cluster' distinguishes it from the cluster-scoped sibling list_cluster_variables without the agent needing to open a 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?

The 'shared by every cluster' clause implies when this tool applies versus cluster-scoped variables, and it notes platform-owned settings are excluded from results, but it never explicitly names an alternative or states a when-not condition. Usage is inferable rather than stated.

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