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

The description adds meaningful behavioral detail beyond the annotations: it discloses the asynchronous acceptance semantics ('returns when the start is accepted') and the latency window ('usually running within 30 to 90 seconds'). The idempotent behavior for already-running servers is consistent with and reinforces idempotentHint=true. It does not repeat the annotation fields verbatim, adding real value.

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 short sentences, each earning its place: the core purpose, the lifecycle/timing context, and the idempotency caveat. The most important information is front-loaded and there is zero wasted wording.

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 single-parameter tool with a 100%-covered schema, an output schema, and annotations covering the safety profile, the description is complete. It tells the agent when to call it, what timing to expect, and how it behaves on an already-running server. Nothing an agent needs to invoke it 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 project_name as 'Name of the project.' The description adds no parameter-specific meaning beyond the schema, which is acceptable given full schema coverage. 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 opens with a specific verb+resource statement: 'Start a project's preview server.' It further differentiates from siblings by explaining the lifecycle context ('Aurora stops the preview server of an idle project') and explicitly contrasting with restart behavior ('A server that is already running is left alone'), which distinguishes it from restart_dev_server. An agent can tell exactly what this tool does and what it does not do.

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 clear context for when to use the tool: when an idle project's server has been stopped by Aurora and needs to be started again. It implies the exclusion that it is not for already-running servers ('is left alone'). However, it does not explicitly name the alternative (restart_dev_server) or state when that sibling would be preferable, so it stops short of a full 5.

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