Add acquiring payment (get payment URL)

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

With no annotations provided, the description carries the full burden for behavioral disclosure. It reveals that the tool creates a payment and returns the payment URL and ids, and that repeated calls with the same session are allowed. However, it does not explain prerequisites, failure modes, hold/charge side effects, or what happens if the session is invalid or expired—gaps that matter for a payment mutation.

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 three short, information-dense sentences. The first sentence states the core action, the second lists the key return values, and the third explains repeatability. Every sentence earns its place with zero 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?

The tool has 7 parameters and nested objects, but the schema covers all parameter semantics. The description provides return values (payment URL, session/transaction ids) and the repeat-call behavior, which is adequate given the lack of an output schema. It could be more complete by noting that the session must be active or by cross-referencing create_acquiring_session, but it is reasonably complete for an existing-session payment addition.

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 100%, so every parameter is already documented in the input schema. The description adds little beyond referencing session_id, which is also in the schema. This meets the baseline but does not elevate it since the tool description itself provides no additional parameter-level meaning.

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 a specific verb ('Add a payment') and resource ('existing acquiring session'), immediately distinguishing it from add_checkout_payment. It also notes the key output (payment URL, session and transaction ids), making the tool's purpose unmistakable.

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 practical usage context: it must be called on an existing acquiring session and can be called again with the same session_id to add more payments. It does not explicitly contrast with add_checkout_payment or other siblings, but the 'acquiring session' framing and the mention of 'existing session' imply the proper workflow after create_acquiring_session.

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