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

With no annotations, the description carries the burden, and it does disclose a real behavioral trait: the cost (1 mcp_call) and the output encoding (JPEG). However it omits key operational facts such as whether a live browser session is required, whether the default session is auto-created, and how the image is returned.

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, front-loaded with the resource and format, followed by the cost caveat. No filler whatsoever.

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?

With no annotations, no output schema, and an undocumented session parameter, the description should explain prerequisites (active session, navigated page) and return mechanics. As written it gives an agent only enough to know what the tool produces, not how to call it successfully.

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 ('session', default 'default') at 0% schema description coverage, and the description says nothing about it — not what it identifies, how to obtain one, or what the default means. The description does not compensate for the coverage gap.

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 ('Screenshot of the current page') plus the output format (JPEG), which implicitly distinguishes it from browser_extract_text and browser_get_html. It doesn't name those siblings explicitly, but the image-vs-text distinction is clear enough to select correctly.

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?

No explicit when-to-use, when-not, or alternative guidance. 'Current page' hints that a page must already be loaded via browser_navigate, but the agent is left to infer that, and nothing indicates when to prefer this over text or HTML extraction.

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