Evaluate JavaScript in the client page

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

Annotations already flag destructive/openWorld/non-idempotent, but the description adds critical context beyond them: unsandboxed, bypasses the write allowlist by construction, gated by the allowEval config flag (directing the agent to check lol_status), and requires an active CDP connection via Pengu Loader. This is exactly the behavioral disclosure an agent needs before calling a dangerous tool.

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?

Front-loads the purpose, then uses CRITICAL/Behavior/Security/Prerequisite labels to structure the warnings efficiently. It is long, but nearly every sentence carries distinct, decision-relevant information.

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 2-param tool with full schema coverage, rich annotations, and no output schema, the description covers purpose, alternatives, destructive/unsandboxed nature, the config gate, and the CDP prerequisite. An agent has everything needed to invoke it correctly.

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%, with both `expression` and `awaitPromise` documented in the schema, so baseline is 3. The description implies single-expression evaluation and return of a result but adds no syntax or format detail beyond what the schema already provides.

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?

States a specific verb+resource: execute an arbitrary JavaScript expression in the CEF renderer context and return the result. It explicitly distinguishes itself from siblings by naming what it is NOT for (LCU REST calls, DOM inspection, REST state queries).

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 when-to-use/when-not with named alternatives: lol_get/lol_request for REST, lol_workflow_* for game actions, lol_dom_query for DOM, and reserves lol_eval for CEF runtime debugging and custom in-page automation. Nothing is left to inference.

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