Spawn a Devin subagent

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

With no annotations provided, the description carries the full burden. It discloses the key behavioral traits: non-blocking (returns immediately), background execution, and parallel support. It does not mention failure modes or permissions, but for a spawn operation this is acceptable and provides useful context beyond the schema.

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 two concise sentences that front-load the core purpose and immediately clarify the asynchronous nature and progress tracking. Every word serves a purpose, with no 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 a tool with five parameters and no output schema, the description provides sufficient context: what it does, that it is non-blocking, and how to monitor progress. It does not specify the return value format, but since no output schema exists and the name parameter serves as a handle, this is a minor gap.

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 already documents all five parameters with descriptions (coverage 100%), so the description adds no additional meaning to them. It does not elaborate on parameter interactions or constraints, so a baseline of 3 is appropriate given the schema's thoroughness.

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: 'Create a new Devin session and start it on a task in the background.' It identifies the resource (a Devin subagent) and the key behavior (asynchronous, parallel-capable), distinguishing it from sibling tools like poll and wait which are for monitoring or managing existing sessions.

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 gives practical guidance by noting it 'returns immediately; use poll to watch progress' and that 'multiple subagents can run in parallel.' This implies when to use it (to launch a new task) and how to follow up, though it does not explicitly name exclusions or alternatives beyond poll.

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