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

Beyond the readOnlyHint annotation, the description discloses that values are never returned and that secret values are never even read. It also explains the security context around credential pasting being refused. This gives the agent an accurate mental model of the tool's safety and behavior.

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?

The description is compact and front-loaded with the core purpose. Each sentence contributes meaningful context: the resource, the privacy behavior, the usage pattern, and the mutation boundary. There is no redundant 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?

The tool has no parameters and an output schema, so the description only needs to convey what is listed and any important behavioral caveats. It does both thoroughly, including the critical guarantee that secret values are never read or returned. Nothing an agent needs to safely call this tool 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?

The input schema has no parameters, so there are no parameter semantics to document. The baseline for a zero-parameter tool is 4, and the description appropriately signals that the tool simply lists all variables without requiring input.

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 clearly states the tool lists the org's reusable variables with their keys and secret status. It is distinct from every sibling list_* tool because no other sibling targets variables, and it names the exact resource being operated on.

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 description explains why and how variables are used: they go into a monitor's header or body as {{ key }} and are resolved at check time to build authenticated checks. It also explicitly says variables are created and edited in the app, not here, which prevents an agent from attempting mutations. It does not name sibling alternatives, but none are direct alternatives for this resource.

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