Arrive at a barrier (free, no auth — the URL is the capability)

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 adds key behavior: idempotent per part, so retrying agents cannot inflate the count. It also clarifies the ctx is handed to the consumer of the released barrier. It does not mention error behaviors, but the disclosed idempotency is valuable.

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?

Two sentences, front-loaded with the primary purpose. Every word earns its place, including the idempotency note and the source of arriveUrl. No fluff.

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 simple 3-parameter tool with no output schema and no annotations, the description covers the essentials: purpose, parameters, idempotency, and relationship to coord_barrier. It doesn't explain return values or failure modes, but given low complexity and sibling context, this is adequate.

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 67%, with arriveUrl lacking a description. The description compensates by explaining arriveUrl comes from coord_barrier and elaborates on ctx as 'whatever you want handed to whoever consumes the released barrier'. The part parameter's example is also reinforced. This adds meaning beyond 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?

The description states a specific verb 'report' and resource 'this part is done', and clearly distinguishes from siblings by referencing coord_barrier as the source of arriveUrl. It signals arrival at a barrier, which is distinct from coord_barrier (creation) and coord_release (release).

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?

It explains how to use: pass the arriveUrl from coord_barrier plus a part name and optional ctx. The context of when to use is implied ('report that this part is done') and the reference to coord_barrier indicates the prerequisite. No explicit exclusions are given, but the guidance is sufficient for a simple tool.

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