lean_run_code

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

No annotations exist, so the description must clarify behavior. It discloses the need for self-contained code and that output is diagnostics or an error message. However, it does not mention runtime side effects, execution context, or persistence, leaving some ambiguity about what executing the snippet might do.

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 concise and front-loaded: a single purpose sentence, two imperative constraint/guideline sentences, and a minimal Args/Returns block. Every sentence contributes meaning without redundant details.

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?

The tool is a simple code runner, and the description covers purpose, usage constraints, and parameter requirements. An output schema exists, so return-value details are unnecessary. It could mention side effects or execution environment, but for this straightforward tool the description is sufficiently complete.

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?

The input schema only lists 'code' as a string. The description supplements this with essential semantics: the snippet must be complete, self-contained, and include all imports and definitions. This compensates for the 0% schema description coverage and guides the agent in constructing a valid parameter.

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 a specific action and resource: 'Run a complete, self-contained code snippet and return diagnostics.' This distinguishes it from sibling tools like lean_build and lean_diagnostic_messages, which handle file-based operations rather than ad-hoc snippet execution.

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?

Explicit guidance is provided: 'Only use for testing outside open files!' and an alternative is suggested by 'Keep the user in the loop by editing files instead.' The requirement 'Has to include all imports and definitions!' adds a clear precondition for correct usage.

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