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

Beyond the annotations (readOnlyHint, openWorldHint, idempotentHint), the description discloses boundary point containment ('boundary points count as contained'), return shape ('Returns one boolean per input point'), and an error condition ('Errors when the polygon is structurally invalid'). This adds substantial behavioral context.

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 four sentences, all information-dense and front-loaded with the primary purpose. Every sentence adds value: purpose, geometry types/purity, boundary behavior, return format, and error condition. No redundancy or fluff.

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?

The description covers return format ('one boolean per input point'), boundary semantics, accepted geometry variants, and error behavior. Combined with the output schema and annotations, an agent has sufficient context to select and invoke this tool correctly.

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 100% for both parameters, so the baseline is 3. The description does not add meaningful parameter-level detail; it merely restates the polygon types already listed in the schema. No additional semantics about point format or polygon properties are provided.

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 opens with 'Test one or more points for containment inside a caller-supplied GeoJSON polygon', which clearly states the specific action and resource. It also enumerates supported geometry types and distinguishes this tool from the geocoding/routing siblings by focusing on pure geometric containment.

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 phrase 'Pure geometry' implies this is for geometric queries rather than place lookups, but no explicit 'use this instead of X' guidance is provided. There is no clear statement of when not to use the tool or how it compares to alternatives like reverse_geocode or search_places.

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