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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is clear. The description adds value by specifying the nature of the output (connections with relationships, actions, triggers, settings, and enabled state), which is useful given the absence of an output schema. It does not mention pagination or rate limits, but these are partially covered by schema parameters (limit, cursor), so the extra contribution is reasonable.

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 concise, with two sentences that front-load the core action ('Return bounded Segment destination connections') and immediately follow with the key data components. Every phrase adds information, and there is no redundant or filler content. It is appropriately sized for a read-only listing 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 absence of an output schema, the description provides a useful summary of the returned data, covering the main aspects an agent would need to understand the tool's result. It does not mention error handling or response envelope, but for a read-only paginated list tool with well-documented parameters, the description is sufficiently complete 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?

Schema description coverage is 100%, so all three parameters (limit, cursor, _apiKey) are already documented in the schema. The description does not add any parameter-specific meaning or examples beyond that. With full schema coverage, a score of 3 is the appropriate baseline, as the description does not need to compensate for missing schema docs.

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 ('Return'), names the exact resource ('Segment destination connections'), and enumerates the data included ('source relationships, actions, triggers, settings, and enabled state'). It also frames the purpose with a question ('Answers which downstream tools receive customer data and how they are connected'), making the tool's intent unambiguous and clearly distinct from sibling tools like segment_list_sources or segment_list_warehouses.

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 gives no explicit guidance on when to use this tool versus alternatives. It does not mention segment_list_sources, segment_list_warehouses, or segment_source_destinations, nor any conditions favoring this tool. The usage is only implied through its name and description, leaving the agent to infer that it is the right choice for listing destination connections.

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