agent_session_start

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

No annotations are provided, so the description carries the full behavioral burden. It discloses that a session is created and that the response includes the id, but says nothing about side effects, whether re-calling with the same agent/goal is idempotent or duplicates, or error behavior for a mutation-style tool.

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 earning its place: definition, return value, and usage trigger come first, with the parent_session_id note last. No filler or redundancy.

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 an 8-parameter creation tool with no annotations and no output schema, the description covers purpose, usage, and the return shape adequately. It omits behavioral details that matter for a creation call, such as what happens to existing sessions or how errors surface.

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 baseline is 3. The description adds genuine meaning only for parent_session_id ('chain a resumed run to its predecessor'), while the other seven parameters are left entirely to the schema.

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?

States a specific verb+resource ('Start a new agent session') and clarifies the domain term as 'a run with a goal', so an agent knows exactly what is being created. It does not explicitly name the sibling it contrasts with (agent_resume), leaving some differentiation to inference.

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?

Gives a clear trigger ('Use when beginning a fresh task that you want to track and resume') plus a specific conditional for parent_session_id. It stops short of stating when NOT to use it versus agent_resume or where a resumed run belongs.

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