set_variable_value

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

Annotations declare readOnlyHint=false and destructiveHint=false, indicating mutation but not destruction. The description adds return format details but does not disclose side effects (e.g., impact on bound nodes), permissions, or reversibility. With minimal annotations, the description provides moderate behavioral context.

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, information-dense sentence that efficiently covers purpose, value types, and return value without redundancy. No wasted words; front-loaded with the core action.

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?

For a simple mutation tool with 3 required parameters and no output schema, the description adequately explains the operation, acceptable value formats, and response. It lacks details on error cases or mode/variableId specifics, but these are largely self-explanatory. The description is sufficiently complete for typical usage.

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 is 100%, but the description adds meaningful detail beyond the schema by enumerating value types with concrete examples (e.g., color with {r,g,b,a} and alias structure). It also clarifies the return shape. This adds value over the schema alone.

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 action (set) and resource (variable's value for a mode), and lists acceptable value types and return value. It fully differentiates from sibling tools like create_variable or rename_variable by specifying mode-specific value setting.

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 does not provide any guidance on when to use this tool versus alternatives (e.g., create_variable, rename_variable). It lacks explicit when-to-use or when-not-to-use context, leaving the agent without comparative direction.

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