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

Annotations already convey this is a non-read-only and non-destructive operation. The description adds meaningful behavioral detail: a newly created line has zero endpoints, publishes nothing, serves no traffic, and draft mode requires draftRevision 0. This goes beyond what the annotations and schema alone state.

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?

Three tight sentences, front-loaded with the core purpose, then behavioral significance, then mode/access constraints. No filler or repetition of schema details.

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 no output schema and moderate complexity, the description covers the key operational implications: no traffic until an endpoint is added, draft mode needs draftRevision 0, and edit access is required. It could mention success/error behavior, but nothing essential for calling the tool correctly is missing.

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 already documents name, lineKey, commitMode, and draftRevision. The description adds value by explaining draft-mode behavior and the specific requirement that draftRevision be 0 for creation, which the schema alone does not convey.

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 opens with a specific verb and resource: 'Create a new versioned line.' It further clarifies what creating a line does (no endpoints yet), which distinguishes it clearly from sibling tools like create_endpoint and duplicate_line.

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?

It explains the core usage context: creating a line alone has no traffic, and adding an endpoint publishes it. It also notes prerequisites like edit access and draft mode requirements. It does not explicitly name sibling alternatives, but the guidance is implied clearly enough.

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