start_session

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

With no annotations, the description carries full responsibility for behavioral disclosure. It states that a session is started and returns a session_id to pass to later tools, which is useful. However, it does not disclose side effects, idempotency, or any permission requirements.

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 sentences, each with a distinct purpose: what the tool does, when to call it, and what it returns. The description is front-loaded and contains no filler.

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 simple one-parameter tool with no output schema, the description covers purpose, usage timing, and return value adequately. Minor gaps like lifecycle closure or invalid agent_id behavior are not critical at this complexity.

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 no description for agent_id, but the tool description's 'for an agent' provides minimal mapping to the required parameter. It adds a little meaning beyond the schema but lacks details on agent_id format or how to obtain it.

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?

Description uses a specific verb 'Start' with a clear resource 'new tracking session for an agent'. It distinguishes itself from sibling tools like end_session by explicitly focusing on initialization, and it mentions the returned session_id.

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?

Explicitly states 'Call this at the beginning of a multi-step agent run', giving a clear when-to-use context. It does not provide explicit when-not-to-use guidance or name alternatives, but the sibling tool list implies the session lifecycle.

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