Evaluate JavaScript in the client page

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

With no annotations provided, the description carries the full burden. It discloses that evaluation bypasses the write allowlist by construction and is gated by allowEval, which is significant behavioral context. It also implies code execution capabilities. It does not mention error handling or side effects, but the key traits are covered.

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 with no filler. It leads with the purpose, then adds a crucial behavioral note about bypass and gating. Every word earns its place, and the structure is efficient.

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 potentially powerful evaluation tool with only 2 parameters and no output schema, the description adequately covers the return value and the prerequisite flag. It does not specify timeout or error behaviors, but those are minor gaps given the simplicity of the interface.

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 schema already provides descriptive text for both parameters ('expression' and 'awaitPromise') with 100% coverage, so the description adds no extra parameter-level detail beyond what the schema gives. The recommended baseline of 3 applies.

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 verb 'evaluate' and the resource 'expression in the client UI's own context', and notes that it returns the value. It also highlights the unique property of bypassing the write allowlist, which distinguishes it from other tools, though it does not explicitly name a sibling.

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 provides a gate condition (allowEval config flag) and points to lol_status for checking it, which is useful. However, it does not offer explicit when/when-not guidance relative to siblings like lol_get or lol_request, leaving the agent to infer when this tool is appropriate.

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