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Validate Expression Tool

validate_expression_tool
Read-onlyIdempotent

Validate Mapbox style expressions by checking syntax, operators, and argument correctness for use in style, filter, layout, or paint contexts.

Instructions

Validates Mapbox style expressions for syntax, operators, and argument correctness

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
contextNoContext where the expression will be used
expressionYesMapbox expression to validate (JSON string or expression array)

Output Schema

TableJSON Schema
NameRequiredDescriptionDefault
infoYesInformational messages
validYesWhether the expression is valid
errorsYesCritical errors
metadataYesExpression metadata
warningsYesNon-critical warnings
Behavior4/5

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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint. The description adds useful behavioral context by detailing what is validated (syntax, operators, arguments), going beyond the schema.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Single sentence that efficiently conveys the tool's purpose with no wasted words. Front-loaded with the core action.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given the existence of an output schema and the tool's straightforward nature, the description covers the necessary behavioral aspects. No gaps identified.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 100%, with both parameters described adequately. The description does not add extra meaning beyond the schema, so baseline score applies.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states the verb 'validates' and the resource 'Mapbox style expressions', specifying syntax, operators, and argument correctness. It distinguishes the tool from siblings like validate_style_tool by focusing on expressions only.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines2/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

No explicit guidance on when to use this tool versus alternatives such as validate_style_tool or preview_style_tool. The description omits context for when expression validation is appropriate.

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

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