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

Goes well beyond the annotations (destructive, openWorld, non-idempotent) by disclosing a safety guardrail (Enter refused on account pages), the return payload (URL and title after the press), and the billing/session model (every started minute costs credits, session ends on close or 3 minutes after the last call). Those are exactly the non-obvious traits an agent needs before deciding to act.

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?

Three front-loaded sentences: action and scope first, key semantics second, then constraints and side effects. No filler, and the credit/session warning is placed after the operational content where it belongs.

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?

With one enum-constrained parameter and no output schema, the description still names the return value, the refusal case, and the session lifetime. Nothing material for correct invocation is missing.

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% with a fully enumerated key list, so the baseline is 3; the description adds real meaning by mapping keys to intents (Tab to next field, Enter to send, arrows for suggestion lists), which the bare enum does not convey.

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 and resource ('Presses one key on the current page in the user's browser on Cotlet') and scopes it to the focused element. The concrete key examples (Tab, Enter, Escape, arrows) separate it cleanly from cotlet_browser_type and cotlet_browser_select without needing their schemas.

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?

Gives concrete when-to-use guidance per key ('Tab to the next field, Enter to send, Escape to close a dialog or pop-up') plus an explicit refusal rule ('Enter on account pages is refused'). It never explicitly says when to prefer cotlet_browser_type or cotlet_browser_select instead, so it stops short of full alternative routing.

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