create_variable

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

The description adds no behavioral context beyond the readOnlyHint=false annotation. It does not disclose whether creating a variable with an existing key overwrites it or fails, nor does it mention any permission requirements. This is a significant gap 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?

The description is a single sentence, immediately front-loaded with the action and resource. Every word earns its place, with no filler.

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?

Given the tool's simplicity (two well-documented parameters, no output schema) and the sibling set clarifying the CRUD context, the description is minimally adequate. However, it lacks important edge-case behavior (e.g., duplicate keys) and explicitly identifies no when-not-to-use, leaving the completeness somewhat shallow.

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 for the two parameters is 100%, and the schema descriptions for 'key' and 'value' already explain their meaning and example values. The tool description adds no additional parameter semantics beyond what the schema provides, so baseline 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 uses a specific verb ('Create') and resource ('custom environment variable in n8n'), clearly distinguishing this from sibling tools like update_variable, delete_variable, and list_variables. It precisely states the tool's function.

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 implies usage for creating a new variable but provides no explicit guidance on when to use it versus updating an existing variable, nor does it mention any prerequisites or alternatives. It lacks exclusions such as 'use update_variable if the key already exists.'

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