Create a new contact segment

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

Annotations only state readOnlyHint=false and destructiveHint=false, so the description carries the behavioral burden. It discloses deprecation, the default-profile fallback, and the inability to target other profiles—critical behavioral details an agent needs before invoking.

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 opening sentence duplicates the tool title, and the second sentence largely restates the first. The deprecation note is valuable and concise, but the early redundancy prevents a higher score.

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?

The description covers the key operational caveats (deprecation, default profile fallback, recommended alternative) and the schema handles parameter details. It does not describe the response shape, but given full schema coverage and no output schema, 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 the schema fully documents all three parameters. The description adds only generic examples of criteria (email, name, subscription status) rather than new parameter-level meaning, so baseline 3 is appropriate.

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 clearly states the operation: create a new contact segment used to organize contacts, with configurable criteria. It also distinguishes this endpoint from profile-scoped alternatives by explicitly stating it cannot target a profile.

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 explicit guidance: the endpoint is deprecated, always falls back to the client's default profile, cannot create segments in other profiles, and the agent should use the alternative endpoint instead. This leaves no ambiguity about when to use or avoid the tool.

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