Get Segment

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

The readOnlyHint annotation already indicates this is a read-only operation. The description adds minimal context beyond the annotation: it specifies the source ('from Resend') and the lookup constraint ('by ID'), both of which are also reflected in the schema. No additional behavioral details such as return format or error scenarios are provided.

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, front-loaded sentence that conveys the essential purpose without unnecessary words. Every word earns its place, making it highly concise and readable.

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's simplicity (one required parameter, read-only, no output schema), the description is sufficient to understand its purpose and usage. It could optionally mention what the response contains, but this is largely implied for a get-by-ID operation, so only minor completeness gap exists.

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%: the 'id' parameter is described as 'Segment ID'. The description does not add any further semantics beyond what the schema already provides, so it meets the baseline but does not exceed it.

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 'Get a segment by ID from Resend' uses a specific verb ('get') and resource ('segment') and explicitly identifies the lookup key (ID). It clearly distinguishes from sibling tools like list-segments, which retrieves multiple segments, and create-segment, which creates a new one.

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 this tool is for retrieving a single segment when its ID is known, which is clear context for use. However, it does not explicitly state when to prefer this over alternatives like list-segments, nor does it mention any preconditions or limitations.

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