capture-screenshot

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

With no annotations provided, the description carries the behavioral transparency burden. It does disclose useful behavior: the screenshot is stored in the MCP resource system, a resource URI is returned, and base64 output is conditional on an environment variable. However, it does not mention that providing a URL causes the browser to navigate first, nor does it state that an active browser/context is required.

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 compact and front-loaded: the core capability appears in the first sentence, followed by return behavior and the conditional base64 detail. Every sentence earns its place with no repeated or extraneous information.

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?

The description explains the return mechanism (resource URI and conditional base64) despite the lack of an output schema, which is helpful. However, it omits important operational context: a browser must already be running or otherwise available, and the navigation side effect when url is supplied is not surfaced in the main description. These are meaningful gaps for an agent deciding whether and how to invoke the tool.

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 schema already documents url, selector, and contextId clearly. The description adds little parameter meaning beyond echoing the current-page versus element distinction, which is already present 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?

The description clearly states a specific action ('Captures a screenshot') with a clear resource scope: the current page or a specific element. It is immediately distinguishable from the sibling get-element-* and browser-evaluate tools, which are about inspecting properties and running scripts rather than producing a screenshot.

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 implies when to use the tool—when a screenshot is needed—but it does not explicitly state when not to use it or name alternative tools. The optional URL, selector, and contextId guidance lives only in the schema, so the natural-language description alone gives no usage context beyond the obvious screenshot case.

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