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 covered. The description adds meaningful behavioral context beyond annotations: the result is 'bounded' to one source and includes specific fields such as 'connection IDs, destination definitions, settings, and enabled state.' This clarifies what the agent will receive without contradicting the annotations.

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 sentences with zero filler. The first sentence front-loads the resource and output fields; the second sentence adds the semantic framing. Every word earns its place.

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 four schema-documented parameters, annotations covering safety, and no output schema, the description provides sufficient return-content context. It mentions pagination only via the schema's cursor field and doesn't explicitly route to siblings, but an agent can correctly invoke this tool based on the provided information.

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%, with every parameter already documented (source_id, limit, cursor, _apiKey). The description does not add parameter-level details, but it isn't required to compensate for schema gaps. Thus the baseline of 3 applies.

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 states a specific verb and resource: 'Return bounded destinations connected to one Segment source' and enumerates the contained fields (connection IDs, destination definitions, settings, enabled state). This clearly distinguishes from sibling tools like segment_list_destinations by scoping to a single source.

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 second sentence, 'Answers where a source sends its customer data,' gives a clear use-case context. The phrase 'connected to one Segment source' signals when this tool applies versus more general list tools. However, it does not explicitly name alternatives or state when not to use it, so it falls short of a 5.

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