spawn_play_open

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

With no annotations, the description carries the full burden and does well: it reveals the default headed mode, the critical failure of headless (no WebGPU adapter, 'One graphics fix away' gate), and that the result reports webgpu status. It also explains why screenshot and input are preferred. It doesn't explicitly state that a screenshot is returned by default, but that is covered in the schema.

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 six sentences and slightly verbose, but every sentence earns its place—covering purpose, usage context, and the headless pitfall. It is well-structured and front-loaded with the primary action, avoiding unnecessary filler.

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?

Given no annotations and no output schema, the description is fairly complete: it explains what the tool does, when to use it, the critical headless limitation, and what the result reports. It does not explicitly mention the default screenshot return (though the schema does), and width/height are not described, but overall it provides substantial context for an opening tool in a Playwright-based workflow.

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 78%, just below the 80% threshold, so the description should compensate. It does add one useful semantic: playUrl resolves from the variant if omitted, and it reinforces the headed parameter. However, width and height remain undocumented in both description and schema, and the description doesn't enhance the other parameter meanings 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?

The description clearly states it opens the live Spawn play URL in a local Chromium via Playwright, using a specific verb 'Open' and resource. It distinguishes itself from siblings like spawn_play_screenshot and spawn_play_input by framing itself as the agent's 'eyes/hands' on the game.

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 strong usage context: it should be used as the agent's primary interface, and it explicitly warns against headless mode because it cannot render WebGPU. It does not mention alternatives by name, but implies this is the entry point before using screenshot/input tools, and gives a conditional note about playUrl resolution.

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