start_session

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

With no annotations, the description carries full behavioral burden. It discloses key traits: starts an embedded server, opens a browser window, and shows live diagram updates. However, it omits lifecycle details like how to stop the session and what happens to the server afterwards, and does not mention the return 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?

The description is three sentences, front-loaded with the primary action. Each sentence adds a distinct piece of useful information: the session start, the embedded server/browser, and the real-time update behavior. No redundant or unnecessary text.

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 accurately explains what happens during the session but leaves gaps around the return value (e.g., session ID or URL) and session termination/cleanup. Given the lack of an output schema and annotations, these omissions mean an agent may not know what to expect back or how to manage the session lifecycle. Adequate for a simple tool but with clear gaps.

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?

The tool has zero parameters, so the baseline score is 4. The description adds context about the session's behavior but no parameter-specific details are needed since there are none.

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 specifies the action 'Start a new diagram session' and the key feature 'real-time preview', distinguishing it from sibling tools like create_new_diagram or export_diagram. The mention of an embedded server and browser window adds specific context that clearly identifies this as a session-launching tool.

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?

No guidance is provided on when to use this tool versus alternatives. It does not reference sibling tools, state prerequisites, or mention when not to use it. The usage context is implied (when real-time preview is needed) but never explicit.

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