list_instances

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

With no annotations, the description carries the burden and explicitly notes that it 'Never returns tokens or other secrets,' adding a behavioral guarantee beyond the schema. It also discloses the scope (server-global) and the content of the list, providing adequate transparency for a read-only list operation.

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?

Three short sentences front-load the main purpose, then add a safety note and a routing tip. No waste.

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 discovery tool with no output schema, the description mentions all relevant return fields and the safety constraint. It is complete enough for an agent to know what the tool returns and how to use the result.

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 single optional 'instance' parameter is fully documented in the schema, and the description reinforces that it is not used for routing here. Since schema coverage is 100%, the description adds no new parameter syntax but usefully repeats the cross-tool routing advice.

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 uses the specific verb 'List' and identifies the resource as 'Coolify instances this server is configured to drive,' with the fields returned ('names, base URLs, default, and per-instance host-ops/destructive flags'). This distinguishes it from sibling tools like list_resources or get_servers by focusing on instances and their routing configuration.

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 states that the instance list is server-global and directs users to pass an instance name to any other tool for routing, which gives clear usage context. It does not explicitly list when not to use this tool or name alternative list tools, but the routing instruction serves as practical guidance.

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