Set env var

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

With no annotations, the description carries the full burden of behavioral disclosure. It usefully states that values are never echoed back and are injected on preview and deploy. However, it omits critical behaviors such as whether setting an existing key overwrites it, whether permissions are required, and what the tool returns on success or failure. These gaps limit transparency for a mutation tool.

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 with no wasted words. The core action is front-loaded, and the additional behavioral notes (injection, no echo) are directly relevant. The structure is efficient and easy to parse.

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 mutation tool with no annotations and no output schema, the description is incomplete. It does not clarify overwrite semantics, persistence across previews/deploys, or what the response contains (even though values are never echoed, the tool may return a success indicator). The simplicity of the tool (3 string params) makes the missing behavioral details more noticeable.

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 0%, so the description must compensate. It references 'app's .env' (clarifying the app parameter) and 'secret/config value' (shedding light on the value parameter), but it does not explain the 'key' parameter (the variable name) or its format. The description partially clarifies two of three parameters but leaves the most essential one ambiguous.

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 'Set a secret/config value in the app's .env' with a specific verb ('Set') and resource ('.env'). The description clearly indicates the action and implicitly distinguishes from sibling list_env (read vs write). The purpose is unambiguous and specific.

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?

No explicit guidance on when to use this tool versus alternatives or when not to use it. The mention of injection on preview and deploy provides some context, but it does not direct the agent to, for example, use list_env to verify existing values or explain scenarios where this tool is inappropriate. Usage is implied rather than explicitly specified.

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