screenshot

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

With no annotations, the description carries the full behavioral burden. It usefully discloses the output encoding (JPEG) and the capture scope (active tab, i.e. viewport), but says nothing about what is returned (bytes, path, base64), permissions, or how the 'fullPage' flag changes the capture region.

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 short sentences, zero filler, with the capability front-loaded and the disambiguation trailing. Every clause earns its place.

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 single-parameter capture tool with no annotations or output schema, the description covers the essentials but leaves the lone parameter and the return value unexplained. Adequate as a minimum viable definition, not complete.

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?

There is one parameter with 0% schema description coverage, so the description must define it. 'fullPage' is never mentioned, and 'screenshot of the active tab' actually implies viewport-only capture, leaving the parameter's meaning and its effect on output size unstated.

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 ('Take a JPEG screenshot of the active tab') with the output format included, and explicitly distinguishes itself from the sibling 'snapshot' tool. An agent can separate this from the other seventeen tools without opening the 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?

Gives an explicit when-not and a named alternative: 'Prefer snapshot for reading; use this for visual checks.' The selection rule is unambiguous and routes the agent to the correct sibling.

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