Show a native host message box (sUNC messagebox)

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

Adds substantial context beyond the annotations: it discloses that the call blocks until dismissal, returns the numeric button code, is type-guarded and pcall-wrapped, and yields { error = 'messagebox is not available...' } when the executor lacks the function. Annotations only flag destructive=true/readOnly=false; the description carries the real behavioral burden.

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-loaded with 'WRITES HOST STATE' and dense but non-repetitive across the clause about blocking/returns, the failure path, and the safety line. It is long, but nearly every sentence carries distinct information; only the Phase/cost/idempotency metadata feels like padding.

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 no output schema, the description still documents the return shapes ({ result } or { error }), the failure message, the verification tool (assert-state), and the mutation safety profile. Nothing an agent needs in order to invoke or interpret the call 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%, so the baseline is 3, but the description adds genuine meaning: it explains flags selects the button/icon style and is the same bitfield as the Win32 MessageBox, and it frames caption and threadContext within a signature. That is real value beyond the schema text.

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: 'pops up a NATIVE OS dialog on the host machine via messagebox(text, caption, flags).' The signature, the blocking behavior, and the returned button code leave no ambiguity about what the tool does, distinguishing it clearly from the execute/eval family of siblings.

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 preconditions ('Requires messagebox', 'Requires: active-client, explicit-mutation-approval') but never states when to prefer this over an alternative such as logging or a non-blocking notification. Usage is implied rather than routed against siblings.

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