list_instances

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

Annotations already declare readOnly and openWorld hints. The description adds contextual value by specifying 'multi-instance / multi-customer support', which clarifies the scope beyond the annotations. No contradictions, and additional traits (like listing all configured instances) are disclosed.

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, well-structured sentence that immediately conveys the tool's purpose. Every word is functional; there is no fluff. It is appropriately concise for a parameterless read-only tool.

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 the tool has no parameters, annotations, and no output schema, the description is complete enough for an agent to understand the action and scope. However, it could potentially clarify that the return is a list of instance identifiers or details, but this is not a critical gap.

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?

There are no parameters, so the description does not need to elaborate on parameter semantics. Schema coverage is 100%, and the description adds no redundant information. Baseline for zero parameters is 4.

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 clearly identifies the resource ('all configured ServiceNow instances'). It distinguishes from sibling tools like 'list_users' or 'list_reports' by specifying the domain of instances and multi-instance/multi-customer support.

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 does not provide explicit guidance on when to use this tool versus other list tools (e.g., when to list instances vs. list users). No alternatives or exclusions are mentioned, leaving the agent without clear context for tool selection.

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