list_environment_variables

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

With no annotations provided, the description carries the full burden for behavioral transparency. It usefully discloses that both process-level and session-scoped overrides are returned, and that session overrides are marked with source: "session". However, it does not explicitly state side effects or safety aspects beyond 'list', which is a read operation.

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 two concise sentences, front-loaded with the primary action and followed by a specific behavioral detail. Every word adds value, with no wasted text or repetition of schema information.

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 is simple with one optional parameter and an output schema. The description adequately explains the purpose and return value distinctions. It could mention the filter parameter or reference the sibling tool, but the schema covers the parameter and the description is otherwise complete for this low-complexity tool.

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 schema description coverage is 100%, with the filter_prefix parameter fully documented as an optional prefix filter, case-insensitive and empty to list all. The description adds no further meaning beyond the schema, so the baseline of 3 applies.

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 tool lists all environment variables visible to the MCP server process, using the specific verb 'list' and resource. It distinguishes from the sibling get_environment_variable by saying 'all', though it does not explicitly name the alternative.

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 provides no explicit guidance on when to use this tool versus the sibling get_environment_variable, nor does it mention any exclusions or alternative suggestions. It simply describes what the tool does without recommending scenarios.

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