Render a map to PNG

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

With no annotations, the description carries the full burden, and it does disclose meaningful behavior: rendering is engine-accurate and the return is an image. It omits other behavioral facts, notably that saveTo writes a file to disk and whether the tool has any side effects, so it is only partially transparent.

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 sentences, no filler, with the core action and its engine-accurate compositing detail front-loaded before the overlay aside. Slightly terse given eight parameters, but every sentence 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 an 8-parameter tool with no annotations and no output schema, the description covers the essence (engine-accurate render returned as an image, overlay semantics) but leaves gaps: image return format, the saveTo write side effect, and behavior of scale/grid/layer options are unaddressed.

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 75%, so the schema already documents most parameters (scale, saveTo, overlay, onlyLayers, showEvents, animationFrame). The description's overlay sentence adds conceptual meaning by mapping overlays to passability/region/terrain, but says nothing about scale, saveTo, showGrid or layer restriction — a baseline 3.

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 ('composite a map ... return it as an image') and adds the distinguishing detail that compositing mirrors engine behavior with autotiles, shadow bits and z-order. It does not, however, explicitly differentiate itself from near-siblings like live_screenshot or get_map, so an agent must infer the boundary.

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 clause 'so layout can be verified visually' implies the intended use case (visual verification of layout), which is useful inferred context. There is no explicit when-to-use/when-not guidance and no mention of alternatives such as live_screenshot for a running game versus this offscreen render.

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