variables_set

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

No annotations are provided, so the description must fully disclose behavior. It states it sets a value and mutates state, but omits details on side effects, error handling, permissions required, or consequences of invalid expressions. This leaves the agent without critical behavioral cues.

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 sentences, efficient and front-loaded. The first sentence defines the action, the second provides a practical use case. No unnecessary words.

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 mutation tool with no annotations, the description is incomplete. It does not explain the behavior when the expression is invalid, the role of frameId, or what the tool returns (no output schema). This leaves the agent with significant gaps.

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%, so the schema already documents all three parameters. The description adds marginal value by clarifying 'lvalue expression' and 'C# expression,' but largely restates the schema descriptions. Baseline 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 clearly states the action ('Set the value of a variable or any lvalue expression') and provides concrete examples ('userId' or 'user.Name'). It distinguishes the tool from siblings (e.g., variables_get, evaluate) by focusing on mutation.

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 mentions a use case ('test fixes by mutating state mid-run'), offering context for when to use the tool. However, it lacks explicit guidance on when not to use it or alternatives (e.g., when to use variables_get or evaluate first).

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