Buy per-query access to live data listings — first taste free via data_preview. Listing: hnfrontpage: Hacker News Front Page (Live) (0.01 USDC/query). Returns fund instructions after data_session_open.
| Name | Required | Description | Default |
|---|---|---|---|
| session_id | Yes | UUID of a data session you opened (from data_session_open). |
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already cover read-only, idempotent, and non-destructive behavior. The description adds meaningful context: it returns fund instructions rather than executing a payment, mentions the specific listing and cost, and clarifies the dependency on data_session_open. This goes beyond what the annotations alone communicate.
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?
Two compact sentences deliver purpose, alternative, specific listing, pricing, and return behavior with no filler. The most important information is front-loaded and every phrase adds value.
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?
Given the tool's low complexity, rich annotations, and single documented parameter, the description covers the essential workflow, the cost, and what to expect as a result. It is somewhat vague about the contents of the 'fund instructions' return value, but this is a minor gap without an output schema.
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?
The only parameter, session_id, is fully described in the schema as coming from data_session_open. The description reinforces the session dependency but does not add substantial new meaning beyond what the schema already provides, so the baseline of 3 applies.
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 the tool buys per-query access to live data listings and identifies the specific listing and price. It distinguishes itself from data_preview by marketing it as a free first taste, but it does not explicitly differentiate from sibling tools like data_session_fund or data_session_attach_escrow.
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 implies the workflow: preview free via data_preview, open a session, then call this tool to obtain fund instructions. However, it does not explicitly state when to choose this tool over data_session_fund or other funding-related siblings, leaving some inference required.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
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Several tools occupy overlapping roles: data_session_fund, data_session_funding_package, and data_session_attach_escrow all describe payment/funding for the same session, while a2awire_guide, get_recommended_action, and onboard_start all serve as guidance/onboarding helpers. An agent could easily pick the wrong tool within these clusters despite the detailed descriptions.
Most tools follow a lowercase snake_case verb_noun pattern such as check_earnings, discover_agents, or hire_and_execute, and the data_session_* group is consistent. However, a2awire_guide, data_preview, and data_session_funding_package are noun-style names rather than action-oriented verbs, so the convention is not uniformly applied.
Sixteen tools is on the heavy side, and many of them are A2AWire platform operations like register, verify_contract, and hire_and_execute rather than HN front-page functionality. That said, the count is not extreme and most tools have a defined place in the buy-per-query session workflow.
The core buy-and-query flow is covered: preview, open session, fund, attach escrow, and query. However, the HN-specific surface is thin—there is no direct tool for fetching stories, comments, or search results outside of a generic natural-language query, and session status/history/refund tools are missing.