purchase_giftPOST /api/purchase. Buy a brand gift code (Apple, Steam, Google Play, … — live list). ext_id required. Never payment_source=stars.
| Name | Required | Description | Default |
|---|---|---|---|
| ext_id | Yes | ||
| offer_id | Yes | ||
| expected_price | No | ||
| payment_source | No | ||
| required_fields | No |
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already mark the operation as non-read-only, idempotent, and destructive, so the description does not need to re-state mutation. It adds a critical value restriction ('Never payment_source=stars') and notes the offer list is live, but it does not disclose charging or irreversibility beyond what 'Buy' implies.
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 short clauses front-load the endpoint and purpose and avoid filler. Every sentence adds some information, though 'POST /api/purchase' is partly redundant with the tool name/title.
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 5-parameter purchase tool with no output schema and zero schema descriptions, this is thin: it omits how to discover valid offers, what expected_price/required_fields mean, and what a successful purchase returns. Annotations provide idempotency/destruction flags but not enough operational detail.
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 0%, so the description carries the burden for five parameters. It adds only two param-related hints—ext_id is required and payment_source must not be 'stars'—and leaves offer_id, expected_price, and required_fields semantically unexplained.
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 states a specific verb ('Buy'), a concrete resource ('a brand gift code'), and gives examples (Apple, Steam, Google Play). It clearly distinguishes the operation from sibling tools like purchase_esim and list_gift_offers.
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 operational constraints ('ext_id required', 'Never payment_source=stars') but does not explain when to prefer this tool over related siblings or when not to use it. Selection context is only implied by the 'gift code' phrase, with no explicit exclusions or alternatives.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
Add one secure layer between your agents and this server.
Most tools target distinct resource-action pairs: card creation, card detail, top-up, eSIM/gift purchase, KYT initiation, KYT polling, and history are all separated. The KYT family is the main risk area, but the descriptions clearly distinguish check, get, checks, and quote.
The dominant pattern is verb_noun snake_case, e.g., list_cards, purchase_gift, topup_card, get_balance. The KYT group is inconsistent—kyt_check, kyt_check_get, kyt_checks, kyt_quote—and set_webhook/rotate_hmac break the pattern slightly, but the overall set remains predictable.
19 tools is above the typical 3-15 sweet spot, but the count is justified by the range of spend rails and supporting operations: cards, eSIM, gift cards, KYT screening, notifications, and webhook management. No tool feels truly redundant, though the KYT cluster adds some bulk.
Core purchase and card workflows are covered: create, topup, details, list, and buy operations exist for cards/eSIM/gifts, plus deposit and KYT screening. However, there is no transaction/spend history, no card freeze or block action, and no explicit purchase status/refund flow, which are notable gaps for a spend-focused server.