Select cells by predicate

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

Annotations declare readOnly, idempotent, and non-destructive hints. The description adds critical context: stateless, bounded region, sample limit of 2,048 cells with truncation disclosure, works on multiple map types, and flip bits ignored. 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 a single paragraph of three sentences, front-loaded with the core purpose, concise with no redundant 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 complexity (5 params, nested objects, output schema exists), the description covers the main concept well but omits details about the 'region' parameter and how it bounds the selection. Minor gap considering the richness of other provided info.

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 low (20%). The description adds meaning for the 'match' parameter by summarizing predicate types and sample limit behavior, but does not explain 'mapPath', 'layerId', or 'region' beyond what schema provides. Partial compensation but insufficient for full clarity.

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 tool evaluates a stateless selection predicate over a bounded tile-layer region and returns the selection as plain data with specific outputs (cell count, bounding box, coordinate sample). It distinguishes itself from siblings by noting the lack of selection id or server-side state, guiding the agent to feed results into region- or cell-based 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 explains that the tool is stateless and that results should be fed into other tools explicitly. It outlines supported predicate kinds (tiles, empty, nonEmpty, magicWand, polygon, compose) but does not explicitly contrast with sibling tools or provide when-to-use vs. alternatives guidance.

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