preview_sketch

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

With no annotations, the description carries the full burden, and it does disclose meaningful side effects: a browser opens, rendering may be inline in MCP Apps clients, and preview is auto-triggered elsewhere. However, it never says whether this mutates sketch state, how seed/params overrides affect persisted data, or what the call returns (no output schema exists) — so the agent can't fully reason about side effects.

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 sentences, each doing distinct work: capability, when to call, and where it renders. The capability statement is front-loaded and there is no 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 a simple 3-param tool with no annotations or output schema, the description covers purpose, call timing, and rendering environment — enough to invoke correctly. It falls short only on the return/aftermath behavior (does the call block, return data, or just open a UI?).

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 100%, and all three params are documented in the schema, so the baseline is 3. The description only loosely gestures at the parameters via 'parameter sliders, color pickers, and seed controls' without explaining that seed and params act as overrides for this preview only.

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 ('Open an interactive HTML preview of a sketch in the browser') and enumerates the interactive affordances (sliders, color pickers, seed controls). This is clearly distinguishable from neighboring tools such as capture_screenshot, open_sketch, and design_preview_at.

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?

Explicitly names the triggering situation ('Call this after update_algorithm'), the condition to avoid it (preview already opens automatically on create_sketch), and the exception ('only call this for re-previewing after updates'). The agent is never left to infer routing.

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