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

Annotations already declare destructiveHint=true, and the description goes well beyond that by disclosing session requirements, refusal behavior ('refuse and start browser connect'), non-debit review mode, failure recovery JSON, and response fields (paid + payment.status). It also lists explicit never-do actions and authentication handling, providing deep behavioral context beyond the structured annotations.

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 description is a single dense paragraph with many clauses, conditionals, and prohibitions, which makes it hard to scan. While most sentences carry important information, the lack of formatting, bullets, or separate sections hurts readability and quick comprehension. It is more exhaustive than concise.

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?

For a complex mutation tool with 10 parameters and no output schema, the description covers extensive ground: session flow, test mode, lucky purchases, clarify gate, review mode, failure recovery, and response fields. Yet it omits detailed semantics for core parameters like store_id, items, idempotency_key, and explanation, and does not specify the full success response shape, leaving it just short of fully complete.

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 40%, so the description must compensate. It adds meaning to lucky, sessionId, choice_set_id, and clarification, and explains SKU selection in lucky mode. However, it does not elaborate on store_id, amount, idempotency_key, items, or explanation, leaving some parameters to the sparse schema. Partial compensation for low coverage earns a 3.

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 clearly states 'Propose or place an order in an allowlisted store using AgentPay coins', providing a specific verb, resource, and payment mechanism. This distinguishes it from sibling tools like create_topup_intent or prepare_dixy_checkout. The added detail about session requirements and review mode reinforces the tool's core purpose without ambiguity.

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 description gives explicit when-to-use guidance: prerequisites (begin_agent_link/poll_agent_link), conditional flows for testMode, lucky purchases, clarifyHint, and review mode, plus clear prohibitions (never begin_agent_link again, never ask the owner to edit settings). It even references sibling tools like present_choices when explaining the clarify gate, leaving little room for incorrect invocation.

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