unreal_capture

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

Annotations already mark the tool read-only and non-destructive; the description goes further by disclosing that no image is sent to Jev, no desktop capture, arbitrary file writing, or camera change occurs. It also names a concrete failure mode (headless NullRHI). This is valuable behavioral detail beyond the static annotations and does not contradict them.

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 carrying distinct information: purpose, prerequisite/failure mode, and side-effect-free behavior. The description is front-loaded with the core action and avoids fluff.

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 tool with one optional parameter and no output schema, the description covers the core behaviors and the key prerequisite/failure case. It states the output is an MCP image with revision metadata, though it does not detail what that metadata contains or how the image is returned. The main weakness is the unexplained parameter, which prevents full completeness.

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?

The single parameter max_dimension is not mentioned in the description at all, and schema coverage is 0%, so the description does not compensate. The schema's title and constraints ('Max Dimension', default 1024, min 64, max 1024) provide some intrinsic meaning, but the description leaves the agent without any guidance on how the dimension applies or why they might adjust it.

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 opens with a specific verb and resource: 'Capture the active Unreal editor viewport as an MCP image with revision metadata.' It clearly distinguishes this capture tool from the many preview and inspection siblings by stating exactly what is captured and adding explicit non-behaviors. This makes the tool's role unambiguous.

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 provides clear context: it requires a rendered level-editor viewport and notes that headless NullRHI returns viewport_unavailable, which signals when not to use it. It also clarifies that the image is not sent to Jev, implying this tool is for direct client consumption. However, it never references a specific alternative tool by name, so the 'when to use versus what' is implied rather than explicit.

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