session_open

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

With no annotations, the description carries the burden of behavioral disclosure. It reveals that the session is persistent and headless, returns sessionId and rate limit, and has a one-time TOS acknowledgment. It could elaborate more on rate limiting or behavior on subsequent calls, but it is largely transparent.

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 only two sentences, front-loaded with the core purpose, and contains no unnecessary words. Every sentence provides essential information.

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 the lack of output schema and low schema coverage, the description does a reasonable job covering key aspects: return values, first-call requirement, and mode restriction. It is complete enough for a session creation tool but could expand on the headless parameter and other login options.

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 schema has 0% description coverage, so the description must add meaning. It explains tosAccepted and the login 'anonymous' mode, but fails to describe the 'headless' parameter or other login enum values meaningfully. Partial coverage leaves some parameters underspecified.

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 action ('Open a persistent Sakata chat session'), the resource ('Sakana chat session backed by headless Chrome'), and distinguishes itself from sibling tools (interrupt, send, close, list) by focusing on session creation.

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 provides specific usage constraints such as the requirement for tosAccepted on first call and that anonymous mode is only available in P1. It does not explicitly list alternatives but the sibling tool names make the context clear.

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