balena_update_variable

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

Annotations already declare readOnlyHint=false, indicating a write operation. The description adds no new behavioral detail such as error behavior, side effects, permission requirements, or value replacement semantics. openWorldHint=true suggests external effects, but the description does not elaborate.

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?

One short, direct sentence with no wasted words. The action is front-loaded and the description is appropriately sized for a simple tool, though it sacrifices substance for brevity.

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?

Missing critical operational context for a mutation tool with no output schema: behavior when variable_id doesn't exist, whether value replaces or appends, authorization needs, or what the return value is. The description is under-specified for an agent to invoke it confidently.

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 does not explain the purpose or semantics of kind, value, or variable_id. The enum values exist in the schema but are not interpreted. The agent receives no additional meaning beyond the bare field names.

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 a specific verb 'Update', a clear resource 'variable', and scope 'existing by ID'. This clearly distinguishes it from sibling tools like balena_create_variable and balena_delete_variable. No ambiguity.

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 on when to use this tool versus alternatives. It does not mention prerequisites, differences from create/delete/list variables, or any conditions that would select this tool. The implied context of updating an existing variable is weak and left to inference.

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