Update 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 disclosure, but it only states the basic update operation. It does not disclose behavior for nonexistent keys, whether values are overwritten atomically, or any permission/rate-limit implications.

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 a single concise sentence with no filler, but it is under-specified for a tool with seven parameters. Conciseness is achieved at the cost of necessary 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?

The tool has seven parameters, no output schema, and no annotations, yet the description only states the high-level purpose. It lacks parameter explanations, edge-case behavior, and return expectations, making it inadequate for reliable invocation.

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% and the description provides no parameter names or semantics beyond 'environment variable'. The seven parameters, including boolean flags like is_literal and is_preview, are completely unexplained.

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 action (update) and resource (existing environment variable for an application), making the tool's purpose specific. However, it does not explicitly distinguish it from the sibling tool upsertEnv, which also updates existing variables.

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 guidance is provided about when to use this tool versus createEnv or upsertEnv, and no prerequisites or exclusions are mentioned. The description only states what the tool does, not when it should be chosen.

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