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

It adds genuinely useful behavior (Square vs. URL handoff, no payment taken, exact return payload), but 'Changes nothing' directly conflicts with annotations declaring readOnlyHint=false, and the tool requires an idempotency_key while declaring idempotentHint=false — an unexplained tension an agent could act on incorrectly. The safety profile presented in prose does not match the structured hints.

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?

Three tight sentences: purpose first, then the branching behavior, then the guarantees and return shape. No filler, and the most decision-relevant fact (what happens on confirm) is front-loaded.

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 no output schema, the description usefully enumerates what comes back (provider, destination, price when applicable, consequence to approve), which is exactly the compensating detail needed. The remaining gap is parameter meaning and failure/prerequisite conditions for a 5-param mutation-adjacent tool.

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 0% across 5 parameters and the description explains none of them: the role of business_id vs. offering_id vs. slot_id, when each is optional, or what handoff_kind actually selects is left entirely to the enum. The required idempotency_key — the single field whose semantics most need explanation given the conflict with idempotentHint — is unaddressed.

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?

Specific verb (prepare) plus resource (reservation/appointment), and it crisply explains the two outcomes: a live Square Appointments connection books on confirm, everything else becomes a provider-hosted URL handoff. That contrast implicitly separates it from confirm_booking and from the other prepare_* siblings without the agent needing to open a schema.

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 'on confirm' phrasing plus 'returns ... for the shopper to approve' makes clear this is the pre-commit, information-gathering step that precedes a confirming call. It stops short of naming confirm_booking explicitly or stating exclusions (e.g., when slots are unavailable, use get_open_slots/check_availability first).

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