Add user variable

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

Annotations indicate readOnlyHint=false, destructiveHint=false, idempotentHint=false, and openWorldHint=trueikuha. The description does not explicitly state that this tool creates a new variable (which is a write operation), but the verb 'Add' implies mutation . It does not add context beyond the annotations, such as potential side effects or authentication needs. Since annotations already cover the safety profile (non-destructive, not read-only), the description adds some value but not rich behavioral context. No contradiction with annotations is present.

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 very short and to the point, with the core action stated first. It includes the vtype mapping which is useful. It is not overloaded with unnecessary content, but it could have added a bit more context on usage without harming conciseness.

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 simplicity of the tool (3 parameters, no nested objects, all required) and the existence of an output schema, the description is adequate for basic usage. However, it lacks any mention of potential error conditions, naming constraints (though schema specifies min/max length), or behavioral notes like whether the variable will be overwritten if the name exists. The annotations cover safety, and the schema covers parameters, so the description is sufficient but not comprehensive.

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 100%, meaning the schema documents all three parameters (name, value, vtype) with descriptions. The description adds the vtype mapping (0-4) which is redundant with the schema's enum description, but it does provide the parameter list in a compact form. The description does not add significant meaning beyond what the schema already provides, so the baseline of 3 is appropriate.

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 states the verb 'Add' and the resource 'user variable', making the core purpose clear. It does not explicitly differentiate from sibling tools like update_user_variable or delete_user_variable, but the resource type is distinct enough that an agent can infer the operation. The description is concise but could be more explicit about the specific action compared to alternatives.

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 the tool is for creating new user variables, which is clear from the name and description. It does not provide explicit when-to-use guidance or mention alternatives (e.g., update_user_variable for existing variables), but the context of sibling tools and the schema (required name, vtype, value) makes the usage reasonably inferable. It lacks explicit exclusions or conditions, so it is adequate but not strong.

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