Capture Real UI Screenshots

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 discloses reduced motion, isolated contexts, blocked outbound network, console error collection, and the important limitation that browsers are not auto-installed. What is missing is the mutation profile — that screenshots are written to disk and may overwrite existing files (only visible via the schema), and nothing about runtime cost or failure modes.

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?

Two sentences, front-loaded with the action and engine, followed by the behavioral guarantees and the key limitation. No filler, and the most decision-relevant constraint (no browser install) is placed last for emphasis.

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 7-parameter tool with no output schema and no annotations, the description covers the environment, safety posture, and prerequisite well. The main gap is return semantics — it says a 'console error inventory' is produced but not whether/how it is returned or where screenshot paths surface in the response.

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 86%, so the schema already documents nearly every parameter including defaults and bounds. The description reinforces 'mobile and desktop' (the viewport defaults) and the localhost/Playwright-install prerequisites, but adds no syntax, units, or semantics beyond what the schema states.

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 gives a specific verb ('capture') plus resource ('mobile and desktop localhost screenshots') and names the underlying engine (Playwright in the target project). It clearly separates this from pure analysis siblings like audit_ui_page, though it never explicitly names compare_ui_screenshots as the read/compare alternative.

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?

'Use Playwright installed in the target project' plus 'Does not install browsers automatically' implies the prerequisite (a local dev server and an existing Playwright install) and one exclusion. However, there is no explicit statement of when to choose this over compare_ui_screenshots or audit_ui_page, so routing is left to inference.

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