list_regions

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

With no annotations provided, the description carries the full burden. It discloses what fields are returned and provides a concrete example of the name-to-ID mapping. It implies a read-only listing operation. While it doesn't mention pagination or error behavior, for a simple list tool this is sufficient context. It adds useful behavioral detail beyond a bare 'Lists regions.'

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 two sentences, with the primary purpose front-loaded and the usage guidance in the second sentence. There is no redundant or unclear language; every clause adds value.

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 with one optional parameter and no output schema. The description covers purpose, output fields, example conversion, and usage context, making it fully self-contained for an agent to select and invoke the 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?

The schema has 100% coverage for the single optional parameter 'tenancyId', describing it as 'Tenancy OCID'. The description adds extra meaning by explaining the default resolution ('default: resolved from the auth provider, same rule as compartmentId'), which is not evident from the schema alone. This enhances the parameter's semantics.

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 function: 'Lists the OCI regions this tenancy is subscribed to (region ID, region key, home region flag).' It uses a specific verb ('Lists') and resource ('OCI regions'), and distinguishes itself from sibling tools that deal with instances, compartments, and networks.

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 explicitly explains when to use this tool: 'Use this to resolve a region name... before passing it as the region argument to other tools.' This gives clear context for selection and indicates the tool is a prerequisite for other region-aware operations.

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