region_get_availability

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

With no annotations, the description carries the burden of behavioral disclosure. It describes the return payload ('available_plans: List of available plan IDs') and implies a read-only operation via 'Get'. However, it doesn't address potential error behavior, invalid region handling, or whether an empty list is expected when no plans are available.

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 well-structured with clear Args/Returns sections and a short usage note. It's efficient, though the closing sentence partially repeats the opening purpose. Overall it earns its length.

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?

For a simple 1-parameter read operation with an output schema, the description covers the essential context: what input is needed, what kind of answer is returned, and when to use it. It doesn't mention edge cases or error conditions, but these are secondary for a straightforward availability check.

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 0%, so the description is the sole source for parameter meaning. It defines region_id as 'The region ID to check availability for' and provides concrete examples ('ewr', 'lax'). This fully compensates for the schema's bare type declaration.

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 first sentence clearly states the action ('Get availability information') and the resource ('a specific region'). It implies a targeted lookup rather than a general list, which distinguishes it from broad tools like region_list and related region/plan tools, though it doesn't explicitly name sibling alternatives.

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 gives a concrete use case: 'useful for checking which instance plans are available in a specific region before creating instances.' This provides clear context for when to call it, though it doesn't explicitly state when not to use it or name alternative tools.

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