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

Annotations supply the safety profile (write, non-destructive, open-world), and the description adds real value beyond them: 'ready when the call returns' discloses synchronous/blocking behavior, the .1 gateway reservation reveals address allocation, and 'Scope: network.write' states the required permission.

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?

Two tight sentences, front-loaded with the core action, then behavioral detail and scope. No filler; every clause carries information.

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 creation tool with no output schema, it conveys sync readiness and permission scope, but doesn't indicate what is returned (e.g., the new VPC id), which matters for follow-up calls like connect_vpc or attach_firewall.

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 already documents cidr and region (67% coverage), and the description adds meaning by explaining the .1 gateway reservation that affects how the cidr is consumed. The 'name' parameter remains undocumented anywhere, keeping it from a 5.

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?

States a specific verb and resource ('Creates an isolated private network'), which is clearly distinguishable from get_vpc, list_vpcs, and delete_vpc by verb alone. It stops short of naming the sibling it complements, so it lands just under a 5.

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?

Usage is implied by 'Creates' and the scope note, and it helpfully points to list_regions for the region slug. However, it never states when to prefer this over alternatives or any prerequisites (e.g., ensure name is unique), leaving conditions to inference.

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