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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint, which covers the safety profile. The description adds useful behavioral context by labeling headless capture as 'experimental' and explicitly stating that analyze returns image data rather than text. However, it does not qualify that vision_route can make the tool return a plain-text description instead of image content, creating a slight gap in the blanket 'NOT a text description' claim.

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 text is short, front-loaded with the core purpose, and avoids redundant restatement of schema fields. That said, the conciseness is achieved in part by omitting the 'diff' action and the vision_route exception, so the structure is economical but not fully representative of the tool's capabilities.

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?

This is a complex tool with 22 parameters and three distinct actions, yet the description only discusses two of them and says nothing about diff. There is no output schema, so the description is a lower source of truth for what each mode returns or requires. The missing diff mode and the unqualified analyze-vs-vision_route statement leave the description incomplete for an agent serving the full schema.

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 input schema has 100% parameter description coverage, so the schema already documents all fields. The description itself adds minimal parameter-level detail beyond naming 'capture' and 'analyze', and does not help understand the 'diff' parameters or the relationship between vision_route and analyze. With complete schema coverage, the baseline of 3 is appropriate.

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 identifies a specific resource ('Godot scene screenshot') and provides distinct verbs for capture ('capture') and analyze ('return the image as MCP image content'). However, the action enum includes a third mode, 'diff', which the description never mentions, so an agent cannot tell from the description that pixel-level image comparison is in scope. Overall clear but incomplete on the full purpose.

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 gives brief per-action meanings for 'capture' and 'analyze', but provides no guidance on when to use this tool versus siblings or when to choose the 'diff' action. It also does not specify conditions like needing a client vision capability or a text-output alternative, beyond a single caution that analyze returns image data, not a text description.

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