capture_image

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

With no annotations, the description carries the full burden and does disclose meaningful behavior: the result is a live MCP image result, nothing is written to disk by default, and cropping/annotation of defined regions is possible. It omits permission requirements, latency/blocking behavior, and what happens when the requested camera or region does not exist.

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?

Four short sentences, zero filler, with the usage directive and the return type front-loaded. The final sentence about cropping/annotating is slightly compressed but still 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 a capture tool with no output schema and no annotations, the description covers the essentials an agent needs: what is produced, that it is not persisted, and that cropping/annotation are available. Missing error/failure semantics and sibling routing are the only real gaps.

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 width, camera, format, region, and annotate are already documented in the schema, making 3 the baseline. The description adds only light cross-context for 'region' and 'annotate' (tying annotation to previously defined regions) and says nothing about the other three parameters.

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 states a specific verb and resource ('Captures a live frame directly as an MCP image result') plus the intent ('visually inspect the hardware'), which is clearly distinct from siblings like capture_sequence or read_text. It does not name or contrast any sibling explicitly, so it stops short of the top score.

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?

'Use this any time you need to visually inspect the hardware' is an explicit trigger condition, which is stronger than implied usage. However, no alternatives are offered: with siblings such as capture_sequence (multi-frame), read_text (text extraction), and measure present, the description never says when a different tool is the better choice.

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