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

Annotations already declare destructiveHint=true/openWorldHint=true, and the description adds substantial context beyond them: it does NOT submit credentials, move funds, or mark paid, payer authentication may require a browser (interactive flow), the method is frozen once an invoice exists, and ambiguous cases escalate to operator review. These are exactly the behavioral traits an agent needs to avoid a costly misfire.

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?

Four short sentences, front-loaded with the core action, then negative scope, then the browser caveat, then the locking/escalation rule. Every sentence carries distinct information with no 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?

With no output schema, the description should ideally say what the caller receives back (checkout URL/ID) — that is the one meaningful gap. Everything else needed to invoke it correctly (precondition, idempotent create-or-retrieve semantics, escalation path) is covered.

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 only 33% (only requestToken is documented), so the description must compensate and only partly does: 'an existing invoice locks the method' adds real meaning to the method parameter, and 'accepted quote' implies taskId. But taskId, the enum choices, and the token argument are never clarified in the description itself.

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?

States a specific verb pair and resource ('Create or retrieve provider checkout') plus the gating precondition ('for an accepted quote'), which cleanly separates it from siblings like accept_quote (upstream) and list_payment_methods (read-only). An agent can pick this tool without opening any other 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?

Gives clear context: only for an accepted quote, an existing invoice locks the method, and an uncertain creation should be routed to an operator. It never names a concrete alternative tool to call instead, so it stops short of explicit when-not/alternatives guidance.

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