Screenshot If Changed

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

No annotations are provided, so the description carries full burden. It discloses key behaviors: conditional return, no image on unchanged, zero vision tokens, first-call baseline establishment, and pinBaseline semantics. It does not mention authentication or rate limits, but those are typically handled elsewhere. The dHash distance and threshold calibration are explained in the schema, not repeated here.

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, front-loaded with the core distinction, then economic benefit, then edge cases like first call and pinBaseline. No waste; every clause adds decision-relevant information.

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 7-parameter tool with no output schema and no annotations, the description is remarkably complete: it covers the conditional logic, token cost implications, baseline establishment, and pinning. It does not explain return structure (e.g., diagnostics), but that is not critical for invocation. All key behavioral aspects are addressed.

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 coverage is 100%, so the schema already fully documents all 7 parameters. The description adds contextual meaning to threshold via the dHash distance reference and pinBaseline behavior (keep reference point fixed), which supplements the schema's threshold calibration examples. Baseline 3 is for high coverage, but the description adds value by explaining the trade-offs and default behaviors conceptually.

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 precise verb+resource+condition: capture the screen only if a perceptual-hash change exceeds the threshold. It clearly distinguishes itself from the plain 'screenshot' sibling by adding conditional capture, and from 'get_screen_diff'/'wait_for_change' by returning an image versus diff metadata.

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?

Explicitly names the use case (polling / 24h monitoring) and the economic rationale (static screens cost 0 image tokens). It describes when the first call returns an image (reason=no_baseline) and the purpose of pinBaseline for fixed reference comparisons, giving clear when-to-use guidance.

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