session_start

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 states the detached process, early return after session id exists, and duration of minutes to hours. This is valuable context. It does not cover failure modes or edge cases, but for a session start, the disclosed behavior is sufficient to set expectations.

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 compact and front-loaded. It opens with the core purpose, then explains the asynchronous behavior, and finishes with practical instructions. Every sentence contributes value; 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?

Given the tool's complexity—a long-running asynchronous process with multiple internal stages—the description adequately covers the key context: detached execution, early return, polling, and cost estimation. It does not describe the output or error handling, but since there is no output schema and the tool is a starter, the provided context is sufficient for typical usage.

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% (all 6 parameters have descriptions), so the schema already provides parameter semantics. The tool description does not add extra details about parameters beyond what the schema offers. Per the baseline rule for high coverage, a score of 3 is appropriate.

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 verb and resource: 'Start a new research session' from a natural-language goal. It distinguishes from siblings like session_status and session_resume by focusing on the initiation action and describing the long-running process. The purpose is unambiguous.

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 explicitly directs the agent to poll session_status for progress and to call estimate_cost to agree on scale before starting. It also implicitly distinguishes from session_resume by focusing on new sessions. These explicit references to sibling tools provide strong usage guidance.

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