spawn

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

With no annotations present, the description carries the burden and delivers the single most important trait: it returns a sessionId immediately and nothing blocks, so the agent knows not to expect an inline result. It omits other behavioral context such as permissions, session lifetime/cleanup (handled by `forget`/`abort`), and failure behavior.

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 short sentences, front-loaded with the core action and followed by the async contract and lifecycle routing. No filler; every sentence carries actionable 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?

For a 7-parameter, no-output-schema tool this covers what an agent most needs: the async contract and the follow-up tools for polling, steering and answering. Residual gaps are minor – return payload shape beyond sessionId and failure/timeout behavior are unstated.

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 schema already explains id, cwd, label, model, tools and extensions in detail. The description adds no parameter-level meaning beyond that (e.g. it never mentions the tools allowlist or model override), so the baseline 3 applies.

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 and resource: "Delegate a task to a pi agent running in the background," which is unambiguous. It implicitly separates itself from `run` via the timing heuristic ("more than a minute"), but never names `run` or `spawn_batch` explicitly, so sibling differentiation is inferred rather than stated.

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 an explicit when-to-use rule ("anything that might take more than a minute") and then routes the agent through the full lifecycle: poll with `status`, redirect with `steer`, answer questions with `answer`. This is exactly the alternative-naming guidance an agent needs to pick and follow this tool correctly.

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