list_instances

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

Annotations already declare readOnlyHint=true, and openWorldHint=true, covering safety and scope. The description adds the 'all configured' scoping and multi-instance context, but does not describe pagination, return format, or other behavioral details. This is acceptable for a simple read-only list, but doesn't exceed annotation coverage significantly.

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 a single concise sentence that front-loads the action and resource. Every word is informative, with no redundancy or filler.

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 very simple (0 params, read-only), and the description accurately captures the core functionality. However, without an output schema, it doesn't mention what the returned list contains (e.g., instance names, URLs), which would be helpful. Overall, it's adequately complete for the tool's low complexity.

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 tool has zero parameters, so the baseline is 4. The description provides no parameter information, but none is needed. The schema already shows no properties, so the description adds no parameter semantics beyond confirming the operation takes no input.

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 a specific verb ('List') and resource ('all configured ServiceNow instances'), clearly distinguishing it from sibling tools like get_current_instance or switch_instance. The parenthetical adds context about multi-instance support, reinforcing its purpose.

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 the tool is for retrieving all configured instances, but does not explicitly state when to use it versus alternatives like switch_instance or get_current_instance. There are no exclusions or alternative references, leaving the usage context implicit.

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