list_regions

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

No annotations exist, so the description carries the full burden of behavioral disclosure. It clearly warns that region names are advisory and downsampled, potentially off by one grid cell, and directs users to exact grid cells for computation. This is a significant, non-obvious behavioral trait disclosed transparently.

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 concise, with the main purpose stated in the first sentence. The second paragraph adds important caveats about precision, which earns its place. It is not overly verbose, though the caveat could be tightened without losing meaning.

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 tool is simple (one optional param, no output schema), and the description provides enough context: what it returns (named regions), optional filtering, and the critical advisory nature of boundaries. It does not explicitly describe the return format, but for a list operation, the purpose is clear and the caveat addresses the main 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 parameter 'with_resource' with no description (coverage 0%), but the description explains it in plain language: 'optionally only those containing a given resource.' This adds semantic meaning to the parameter, compensating for the missing schema description.

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's purpose: listing named map regions with an optional filter for a resource. 'Named map regions, optionally only those containing a given resource' is specific about the resource ('map regions') and the verb ('list'). It does not explicitly differentiate from sibling tools, but the resource and filtering behavior are evident.

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 provides practical guidance on when to use the tool: 'Use them to talk about places, not to compute with' and contrasts with exact grid cells available in node rows. This gives context for appropriate usage, though it does not name alternative tools or explicit exclusions.

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