start_session

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

Despite no annotations, the description discloses key behaviors: browser window opening, editor loading, WebSocket connection establishment. It does not mention potential destructive actions, but as a session starter, destruction is unlikely.

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 concise with bullet points and numbered steps, though some redundancy exists between the first sentence and the steps. Still clear and efficient.

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?

No output schema exists, but the description covers post-call behavior adequately. It does not mention return values or error conditions, but for a simple initialization tool, this is acceptable.

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 input schema has 100% coverage with a description for sessionId. The description adds significant meaning: default session behavior and ability to open multiple sessions.

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 tool's verb ('Start browser preview and open Excalidraw editor interface') and resource ('Excalidraw editor'), and distinguishes it from sibling tools like add_elements by being the session initialization 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?

The description explains multi-session support and provides after-call steps, but lacks explicit 'when not to use' guidance. However, the context of use for session management is clear.

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