glass_start

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

With annotations only indicating readOnly=false, openWorld=true, and destructive=false, the description carries the burden and handles it well. It discloses that the tool builds and launches processes, may spawn extra accessibility-bus processes, defaults behavior by host, and can follow a window handed off to an unrelated process — all useful behavioral context beyond the raw annotations.

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?

Four dense sentences, with the core purpose and return value front-loaded. Every sentence adds useful guidance: backend choice, a11y behavior, and window_hint semantics. No filler or restatement of schema details.

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 complex 9-parameter tool with a nested object and no output schema, the description covers the key behavioral decisions, default selections, platform scope, and how to locate the correct window. Combined with the very rich input schema, an agent has enough context to invoke the tool correctly without guessing.

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 schema already documents every parameter thoroughly. The description adds value by synthesizing the most important defaults and decision points: backend defaults to the host, a11y is on by default, and window_hint disambiguates windows or handles process handoff. This is modest but real added meaning beyond the schema.

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 opens with a specific verb plus resource ('Build, launch, and locate a native GUI app') and states the return value ('returns its window geometry'). It clearly distinguishes glass_start from the sibling tools by framing it as the app-launch entry point rather than an inspection or interaction tool.

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 gives concrete usage direction: pick a backend with the `backend` param, pass `a11y:false` for pixel-only apps, and use `window_hint` when multiple windows appear or the process hands off to another process. It does not explicitly name when not to use this tool or contrast it with alternatives, so it stops short of a 5.

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