Create a barrier / fan-in (free — workspace op)

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

With no annotations, the description fully discloses behavioral traits: the arriveUrl is a capability that lets sub-agents arrive but not read/delete the workspace, exactly one webhook fires with all collected context, and a partial event names missing agents on TTL expiry. It also clarifies that timeout is intended behavior, not an error.

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 yet packs essential information: the core purpose, the security model, the webhook behavior, and the timeout semantics—all without unnecessary words. It's front-loaded with a clear summary and then adds specifics in a structured flow.

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?

The description covers key operational details: the arrival capability, webhook aggregation, partial events, and timeout semantics. However, it omits any explanation of the return JSON structure (beyond 'arriveUrl') and leaves several parameters (label, secret, workspaceId) semantically undefined. Given no output schema, these omissions prevent a perfect score.

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 coverage is only 17%, so description must compensate. It explains the meaning of 'parts' (how many sub-agents) and ttlSeconds (timeout), and implies webhookUrl (fires one webhook). However, label, secret, and workspaceId are left unexplained, and webhookUrl isn't explicitly linked to the parameter, leaving gaps despite partial compensation.

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 tool creates a barrier/fan-in, with a concrete use case ('wake me when all N of my sub-agents finish') and returns an arriveUrl. It distinguishes this parent-side coordination tool from siblings like coord_arrive by describing the barrier-creation role and the capability it hands out.

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 provides a clear context for use: coordinating N sub-agents and receiving their aggregated context when all finish. It doesn't explicitly mention when-not-to-use or name alternatives, but the usage intent is unambiguous, earning a 4 rather than a 5.

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