safari_screenshot

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

No annotations are provided, so the description carries the full burden of behavioral disclosure. It adds genuinely useful behavioral context beyond the schema: the operation is EXPENSIVE, returns a base64 JPEG, and maxWidth downscaling reduces token cost. It does not mention response shape details, but for a non-mutating screenshot tool the cost/format/token disclosures are the key traits.

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 earning its place: purpose+format, cost warning with explicit alternative routing, and a practical parameter tip. The most decision-critical info (expensive, use snapshot instead) is front-loaded, and there is zero 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?

For a simple 3-param tool with full schema coverage and no output schema, the description covers the critical decisions: when to use it, what it returns, and how to control cost. Minor gaps — no explicit statement of what the agent should do with the returned image beyond 'verify' — are acceptable given the schema already documents all parameters.

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 the baseline is 3. The description adds value beyond the schema by giving concrete maxWidth guidance ('Pass maxWidth (e.g. 1024) for layout checks — far fewer tokens'), which ties a parameter to a specific use case and outcome. The receipt and fullPage params receive no additional description, but they are already fully documented in 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?

Description states a specific verb+resource ('Take a visual screenshot') plus the output format ('base64 JPEG'), which is concrete and unambiguous. It names the sibling distinction (safari_snapshot) so the agent can tell this tool apart from the nearest alternative without opening either schema.

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?

Explicit when-to-use and when-not-to-use: 'use safari_snapshot instead for most tasks' and 'Only use screenshot when you need to verify visual layout, styling, images, or colors that snapshot can't show.' It names the alternative directly and gives the condition that selects it, so no inference is required.

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