envvar

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

The description discloses that sensitive values are automatically masked, which is a key behavioral trait. However, it does not mention error cases (e.g., variable not found) or behavior when both parameters are provided. No annotations exist to compensate.

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 extraneous information. The purpose is front-loaded and every sentence adds value. Highly efficient.

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?

Despite no annotations or output schema, the description covers the core functionality and security feature. It lacks error handling details, but for a simple read tool it is reasonably complete.

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 description adds value beyond the schema by explaining the overall functionality: single variable by name vs listing with filter. Schema coverage is 100%, so the baseline is 3, but the description clarifies the relationship between parameters and the two usage modes.

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 identifies the verb 'Reads' and the resource 'environment variables', and explains the two modes: single variable by name or list all with optional filter. It distinguishes itself from siblings as the only environment variable reading tool.

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. There is no mention of what not to do or comparison with other tools, leaving the agent to infer usage from the tool name and context.

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