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

Annotations only declare the generic profile (destructive, not read-only, open-world). The description goes well beyond: invite sends the phone an SMS, the member is notified once when covered or removed, cover counts only while the gym plan covers the place up to its cap with normal payment beyond it, no payment is taken here, and a connected Phorme account owning the place is required. These are exactly the side effects and prerequisites an agent needs.

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?

Front-loaded with the triggering situation and packed with signal, with no filler sentences. It is a dense single paragraph though, mixing invocation guidance, side effects and billing caveats, so scanning is slightly harder than a structured layout would be.

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?

With an output schema available, return values need not be explained, and the description still covers auth prerequisites, the confirmation gate, notification side effects, and the billing cap. Nothing essential for correct invocation is missing apart from the sibling-tool routing.

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 already 80%, so the baseline is 3, but the description adds real meaning: phone is specifically for invite, member_id is for approve/remove and comes from action=list, and confirmation must be true only after the owner verbally agrees. That maps the enum values to their required parameters in a way the schema does not.

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 concrete verb set (list/invite/approve/remove) against a specific resource (one member's cover on the owner's gym plan), so an agent knows exactly what the tool does. However, it never names the obviously related sibling set_member_cover, so the one-member-vs-bulk distinction has to be inferred from the title.

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 clear when-to-use context ('an owner on the gym plan wants to see who is covered... or to invite, approve or remove one member') and even a sample utterance. It also prescribes the read-back-and-confirm protocol for the mutating actions. It stops short of naming when NOT to use it or pointing at an alternative tool.

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