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

With no annotations, the description carries the full behavioral burden and does well: it discloses that the server determines the amount (never the caller's named amount), charges off-session, and returns either 'succeeded' (listing enters review) or 'requires_action'. It omits auth prerequisites, idempotency, and failure handling, keeping it short of a 5.

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?

A single dense sentence front-loads the action and the charging behavior with no filler. It is slightly crammed with multiple clauses (entitlement, off-session charge, two outcomes, fallback tool), but every clause earns its place.

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 payment mutation tool with no annotations and no output schema, the description supplies the outcomes an agent needs. The remaining gap is the unexplained 'id' parameter and absent failure/auth behavior, but the core call contract is 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 coverage is only 33%: the 'session' param is documented in the schema, but 'id' and 'paymentMethod' are not. The description compensates for 'paymentMethod' (explaining it is a pm_... id the agent is entitled to use) but leaves 'id' entirely unexplained, so the coverage gap is only partially bridged.

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 action (send a Stripe payment method id) and effect (the server charges the SITE's price off-session), naming the resource unambiguously. It explicitly distinguishes itself from sibling listing_pay_card by routing 'requires_action' outcomes there, so an agent can separate the two without opening either 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 for use (a Stripe payment method the agent is entitled to use) and names listing_pay_card as the fallback when a human is needed. It stops short of contrastive guidance against listing_pay_usdc or listing_confirm_usdc, so the alternative selection is only partially covered.

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