Capture frame

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

readOnlyHint=true already tells the agent this is a safe, non-mutating call, so the bar is lower. The description adds the useful fact that output is a PNG image of the *current* frame, but says nothing about how the image is returned (inline/base64 vs. file path), timing/latency, or whether it captures a live or last-rendered frame.

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?

A single short, front-loaded sentence with no filler; the essential noun (PNG image) and scope (current frame) come first. It is a fragment rather than a full sentence, but nothing is wasted.

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 output schema, the description usefully declares the return type (PNG image), which is the key contract detail for a capture tool. However, the delivery mechanism of that image and any precondition for a valid capture are left unstated, so it is adequate but not fully 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?

The tool takes zero parameters, so there is nothing for the description to disambiguate; the 4 baseline applies. No misleading parameter claims are made.

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 concrete action (screenshot) and an exact artifact (PNG image of the current frame), which is enough for an agent to distinguish it from state/step/replay siblings. It does not explicitly contrast itself with the nearest sibling (game_frames), so it stops short of a 5.

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?

There is no guidance on when to call this versus game_frames, game_state, or game_step, and no stated preconditions (e.g. game must be running or paused, frame must be rendered). Only an implicit sense of usage is conveyed.

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