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

Annotations already declare readOnlyHint=true, destructiveHint=false, and idempotentHint=true. The description adds that the source layer is untouched and a new layer is created, confirming the non-destructive behavior. No contradictions with annotations.

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 description is two sentences long—the first conveys the core functionality, the second provides a usage example. No redundant words or information. Every sentence 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?

Given the tool's simplicity, the annotations cover safety, and the schema documents parameters, the description is sufficient. It does not mention that the new layer will be added to the map, but that is implied by 'Create a new layer'. Lacks a minor detail but otherwise complete.

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 67%, with selection and newLayerId already documented. The description mentions 'within the supplied polygon', which ties to the selection parameter, but does not elaborate on map_id or sourceLayerId. The added value beyond the schema is marginal.

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 states the verb ('Create'), the resource ('new layer'), and the specific operation ('features within supplied polygon'). It also provides a concrete use case ('show me only the X inside this country/bbox/hand-drawn shape'), which distinguishes it from sibling tools like filter_layer (attribute-based filtering).

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 explicitly says when to use the tool ('show me only the X inside...'), providing a clear context. It does not explicitly mention when not to use it or list alternatives, but the use case differentiation is clear enough for an agent to select appropriately.

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