Add or update environment variable

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

The description discloses the API call details (PUT endpoint) and implies idempotent behavior ('add or update'), which aligns with the idempotentHint annotation. The scope limitation adds transparency beyond annotations, with no contradictions.

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 three concise sentences, each adding value: title restatement, scope clarification, and API endpoint. No redundant or unnecessary text.

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 simple tool with 3 required parameters and no output schema, the description covers purpose, scope, and API action. It does not detail behavior for conflicting updates or generateValue, but the schema covers that.

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 coverage is 100%, with each parameter described in the schema. The description adds minimal extra meaning beyond what the schema provides (e.g., 'particular service'), so a baseline score of 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?

The description clearly states it adds or updates an environment variable for a specific service, using a specific verb and resource. It differentiates from env group variables by noting it only applies to variables set directly on the service.

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 explicitly states the tool is for environment variables set directly on the service, not for those in linked environment groups, providing clear context for when to use this tool versus others targeting env groups.

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