capture_screenshot

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It effectively describes key behavioral traits: the tool is read-only ('Side effects: none (read-only)'), has prerequisites ('requires an active Chrome tab'), and specifies the return format ('base64 encoded image in specified format'). It doesn't mention rate limits or error conditions, but covers the essential safety and operational context.

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 well-structured and front-loaded with the core functionality. Every sentence adds value: the first explains what the tool does, the second covers side effects and prerequisites, the third specifies the return format, and the fourth provides usage context and alternatives. There's no wasted text.

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 tool with no annotations and no output schema, the description provides good contextual completeness. It covers purpose, behavioral traits, prerequisites, return format, and usage guidelines. The main gap is the lack of output schema documentation, but the description compensates by specifying the return format. It could potentially mention error cases or limitations.

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?

The input schema has 100% description coverage, providing detailed documentation for all three parameters. The description doesn't add any parameter-specific information beyond what's already in the schema, so it meets the baseline of 3 where the schema does the heavy lifting.

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 the tool's purpose with specific verbs ('captures a visual representation') and resources ('current page viewport or entire page as a base64 encoded image'). It distinguishes this tool from siblings by contrasting it with 'inspect_dom' for HTML structure and 'get_performance_metrics' for rendering metrics.

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 explicit guidance on when to use this tool ('to visually verify UI state, layout, or rendering') and names specific alternatives ('inspect_dom' for raw HTML structure, 'get_performance_metrics' for rendering metrics'). It also includes prerequisites ('requires an active Chrome tab').

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