delimit_screenshot

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

Discloses side effects: gated by require_premium, launches headless Chromium, writes PNG to specific path. No annotations provided, so description carries full burden; lacks mention of rate limits but addresses key behaviors.

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?

Description is brief, well-structured with labeled sections (when to use, when not, sibling contrast, side effects). Every sentence adds value.

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 output schema existence, description covers purpose, usage boundaries, side effects, and sibling contrast. Sufficient for an agent to understand and use the tool correctly.

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%, so baseline is 3. Description does not add extra meaning beyond the schema's own parameter descriptions.

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?

Description clearly states 'Take a screenshot of a URL using headless Chromium (Pro)', specifies the action, resource, and technology. Contrasts effectively with sibling delimit_screen_record.

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 lists when to use (audit evidence, visual regression, documentation) and when NOT to use (time-based recordings, rendered HTML), naming the alternative sibling tool.

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