hubspot_list_instances

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

With no annotations provided, the description carries the full burden. It explicitly declares 'READ-ONLY' and specifies the kinds of information returned (portal names and account ids). This goes beyond the empty schema and is especially valuable for a no-parameter tool where side effects are a primary concern.

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 short sentences with no filler. The core action, return contents, safety hint, and usage guidance are all included efficiently and front-loaded.

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 zero-parameter list tool with no output schema, the description fully conveys what the agent needs: the purpose, the data returned, the read-only nature, and the recommended first step. Nothing critical is missing for correct invocation.

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 schema already covers everything. The description appropriately focuses on return content rather than parameter details. This matches the baseline for a no-parameter tool.

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 and resource: 'List which HubSpot portals are connected' and indicates the key return fields: names and account ids. It clearly differentiates from sibling tools like hubspot_list_objects and hubspot_list_owners by focusing on portals/instances rather than objects or owners.

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 instructs the agent to 'Call this first to see what portals are available,' establishing a clear usage context. It does not explicitly name alternatives or state when not to use it, but the directive is strong enough to guide selection among siblings.

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