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

With no annotations at all, the description carries the full burden and meets it thoroughly. It discloses the cursor advancement contract, oldest-first ordering, empty-poll behavior, 15-minute refresh cadence, dedupe rules by `id` and `cluster_id`, and the exact paid-call negotiation flow. Nothing about the tool's behavior is hidden.

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 dense but every sentence earns its place. It front-loads the core loop contract, then filters, cadence, dedupe, and payment details. The reference to `/skills/news.md` is a small bonus, not padding.

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?

This is a stateful, payment-gated polling tool with no output schema, yet the description supplies everything needed to call it correctly across repeated invocations. It covers edge cases like 'nothing new still returns a complete answer' and specifies the exact cursor/payment semantics that would otherwise be opaque.

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 the schema already documents every parameter. The description still adds meaningful semantics beyond the schema: `since` must be omitted on the first call, `next_cursor` is an opaque token to store and never parse, and `x_payment` requires a sign-then-call sequence. This pushes it above the baseline 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 names the polling loop as a distinct resource and specifies an exact cursor-based protocol, which is far more informative than a generic 'poll news' statement. However, it never explicitly names `news` or `news_batch` as the one-shot alternatives, so sibling differentiation is implied rather than stated.

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 an explicit decision tree: first call omits `since`, every later call passes `next_cursor`; the agent may follow the whole pile, one `category`, or a `topic` tape; and the payment flow is spelled out as a two-step dance. It even points to the `pricing` tool as the alternative for listing prices at once.

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