vpc_list_by_region

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

No annotations are provided, so the description carries the full burden of behavioral disclosure. It only states the basic operation and return type. It does not disclose potential limitations like pagination, sorting, access scoping (e.g., only user-owned VPCs), or error conditions. For a list operation, this is a meaningful gap that could lead an agent to assume an unbounded or fully detailed response.

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 and well-structured. It leads with the core purpose, then uses an Args section for the parameter and a Returns section for the output. No redundant or vague sentences. Every part earns its place, making it easy for an agent to parse quickly.

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 that an output schema exists (as indicated by context), the description need not enumerate return fields. It covers the input parameter and the general shape of the output ('Combined list'). For a simple list-by-region tool, this is sufficient. The only minor gap is lack of mention of pagination or result limits, but these are not critical for a typical list operation and the output schema likely handles field details.

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 input schema provides only a 'string' type for region with no description (0% schema coverage). The description fully compensates by explaining the parameter's purpose and providing concrete examples of valid region codes (ewr, lax, fra). This adds meaningful semantics beyond the schema, enabling correct invocation without external knowledge.

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 action ('List') and the resource ('VPCs and VPC 2.0 networks') and scopes it to a specific region. It distinguishes this tool from other VPC operations (create, update, delete, attach, etc.) and from other list-by-region tools for different resources. The region parameter is exemplified with real codes, making the purpose unambiguous.

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 implies when to use this tool: when you need a combined listing of VPCs and VPC 2.0 networks for a given region. It does not explicitly name alternatives or state when not to use it, but given the tool's unique purpose among siblings (there is no other VPC list tool), the usage context is clear enough. It also provides region code examples, which helps selection.

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