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

Annotations already declare readOnlyHint=false, destructiveHint=false and idempotentHint=false, so the description earns credit by adding real behavior: the SMS delivery, the identity-match requirement, and the enumeration-safety disclosure that 'the answer is the same whether or not the details match.' It could go further on error/rate-limit behavior, but the match-invariance note is genuinely useful beyond structured fields.

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 purpose is front-loaded, but the first sentence is tangled ('for a conversation with no booking action_id that still works') and the valuable enumeration-safety point is buried at the end. Roughly the right length, but not optimally structured.

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 present, return values need no explanation, and annotations cover the safety profile. The description supplies the matching logic, the SMS flow, and the match-invariance behavior, leaving only minor gaps like practice_slug meaning and failure modes.

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 description coverage is only 20% (only patient_phone is documented), so the description carries more burden. It does map the matching inputs ('the mobile number, name and date of birth') to parameters and implies all must match, but practice_slug is never explained and format expectations aren't clarified. Partial compensation only.

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 uses a specific verb+resource ('Text a patient one link to see, move or cancel the appointments they already have') and names the sibling it hands off to (list_xona_appointments). An agent can identify this as the SMS-link entry point distinct from list/change tools. The phrase 'for a conversation with no booking action_id that still works' is murky, which keeps it short of a 5.

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 a clear triggering condition ('a conversation with no booking action_id') and describes the downstream sequence (patient taps link, presses Show my appointments, then list_xona_appointments reads). It does not state when NOT to use it versus siblings, so it stops short of a 5.

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