Marks an ignored area inside a monitored region by drawing a rectangle, and resets the region's sample to prevent mismatched comparisons.
Ask the person to draw a rectangle inside an existing region that should be ignored (a clock, a spinner, a caret). Forgets the region's last sample, since masked grids are not comparable to unmasked ones.
| Name | Required | Description | Default |
|---|---|---|---|
| name | Yes |
Changes observed during successful MCP inspections.
v0.1.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations provided, the description carries the full burden. It discloses two important behavioral traits: the operation is interactive ('Ask the person') and it invalidates the region's last sample, explaining why masked grids are not comparable. This is meaningful side-effect disclosure, though it does not mention irreversibility or whether an existing mask is replaced.
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 concise sentences with no filler. The primary action is front-loaded, the use-case examples are compact, and the side effect is explained in a single, purposeful second sentence. Every part adds value.
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 single-parameter tool, the description covers the action, the interactive nature, the target scenario, and a key side effect. However, it lacks explicit parameter-to-region mapping and does not describe what happens after drawing or what the tool returns, leaving some operational ambiguity.
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 schema has one required string parameter, `name`, with no description coverage. The description says 'inside an existing region' but never states that `name` must identify that region, nor does it clarify what value to pass. The parameter semantics are therefore left mostly to inference.
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 clearly communicates an action: ask the person to draw a rectangle inside an existing region so that part is ignored. The examples (clock, spinner, caret) and the mention of 'masked grids' make the mask-specific purpose clear and distinguish it from the sibling sampling/region tools.
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 implies the tool should be used when an existing region contains a distracting element, and it explicitly requires the region to already exist. However, it does not name alternatives or state when not to use this tool, so the guidance is mostly implicit.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.