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

With no annotations supplied, the description carries the full behavioral burden and does so thoroughly: it explains the customer-facing side effects (one arrived text, one arrived email), the conditions that govern them (on-the-way notices on/off, email only when an address exists, do-not-email suppression), and idempotency ('A repeat call does not send again'). That is exactly the side-effect disclosure an agent needs before invoking a state-changing tool.

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 action and its trigger are front-loaded, followed by authorization and then notification consequences in short declarative sentences. The text/email detail runs slightly long, but each sentence conveys distinct conditional behavior rather than filler.

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?

An output schema exists, so return values need not be explained, and the description covers permissions, notification side effects, and repeat-call behavior. It leaves minor gaps, such as whether arrival records a timestamp or how an unauthorized visit_id is rejected, but nothing that would cause a wrong invocation.

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?

There is a single required parameter, visit_id, whose name and UUID type make its meaning largely self-evident from the schema. The description reinforces it by tying calls to a specific visit the caller is assigned to or owns, but adds no format or lookup guidance beyond that.

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 opens with a specific verb and resource: marking that a worker has arrived at a visit, triggered by the worker telling their agent. That framing distinguishes it from adjacent lifecycle tools such as visits_start, visits_done, and the on-the-way tools without needing to name them.

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 gives explicit trigger conditions ('when they tell their agent, for example I am here') and precise authorization rules: a worker may only call it for a visit they are assigned to, while the owner or office may call it for any visit in the shop. It stops short of naming sibling alternatives (e.g. on-the-way vs. done) or stating what happens if the call is invalid.

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