add_contact_to_segment

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

No annotations are provided, so the description carries the full burden of behavioral disclosure. It states the action and POST endpoint but does not mention idempotency, duplicate handling, permission requirements, validation errors, or what the response indicates. This leaves significant behavioral ambiguity for a mutation tool.

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 with no filler. It conveys the core action and the endpoint efficiently, making it easy for an agent to parse quickly.

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 simple two-parameter tool, the description plus fully documented schema is minimally sufficient. However, with no output schema and no annotations, it lacks practical context such as whether adding an existing membership errors or is a no-op, and what a successful response contains.

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%, and both parameters have clear descriptions ('The contact id.' and 'The segment id.'). The tool description adds no additional parameter meaning, but the schema already provides sufficient semantics for a straightforward two-parameter operation.

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: 'Add a contact to a segment.' It unambiguously identifies the action and clearly differentiates from the sibling remove_contact_from_segment, which is the inverse operation. The HTTP endpoint further confirms the intent.

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 when to use the tool: to associate an existing contact with an existing segment. However, it does not explicitly state prerequisites, exclude alternatives, or mention behavior when the contact is already in the segment. The usage context is clear but not fully elaborated.

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