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

The description adds valuable behavioral context beyond the annotations: unsetting triggers a rollout, reserved variables are protected from removal, and empty-string assignment is meaningfully different. While destructiveHint=false and the word 'Remove' could seem tension-worthy, the description scopes the operation to configuration, not data destruction, so there is no actual contradiction.

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?

Three tight sentences, with the core action and rollout effect in the first sentence and all routing/exclusion guidance in the remaining two. There is no filler or repetition of schema content.

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 two-parameter tool with a simple action, the description covers the necessary inputs, the rollout side effect, the key exclusions, and the secret alternative. There is no output schema, but the behavior is sufficiently unambiguous without needing to document return values.

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 already describes both parameters fully (app_id and key), so the description does not need to repeat them. It adds the qualifier 'plain environment variable' to distinguish from secrets, but no extra parameter-level syntax or constraints are introduced. Baseline 3 is appropriate given 100% schema coverage.

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 states the specific verb 'Remove' and resource 'single plain environment variable from an app', and distinguishes it from the secret-removal sibling by naming unset_app_secret. It also specifies that reserved Dockhold-managed variables cannot be removed, leaving no ambiguity about what this tool does.

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 gives an explicit alternative: 'For a secret, call unset_app_secret instead.' It also clarifies that removing a variable is not the same as setting it to an empty string, and enumerates exclusions (PORT, DATABASE_URL, DATA_DIR, and the app's address), making when-to-use and when-not-to-use very clear.

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