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 does meaningfully well: it discloses the $0.01 USDC per-call cost, the x402 payment mechanism and exactly where the payment proof goes (_meta["x402/payment"]), and the existence of a free 3-row preview via sample=true. What it omits is anything about response shape, pagination, or failure/refund behavior on a paid call.

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?

Front-loaded with the core value proposition, then routes, then pricing — a sensible order for an agent scanning for cost and capability. It is dense and slightly telegraphic in the route listing, but no sentence is 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?

For a 3-parameter tool with a nested params object, no annotations, and no output schema, the description covers payment, preview, and route semantics well enough to call it correctly. It stops short of explaining what a returned 'daily answer' looks like or the meaning of route-specific params like 'theme' and 'table.'

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 100%, so a 3 would be the baseline, but the description goes beyond the schema by attaching query parameters to specific routes (/today takes table, theme, limit; /history takes since*, table, theme), which the schema does not enumerate. The asterisk on 'since*' is left unexplained, a minor gap.

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 resource and framing: a daily delta of "what jumped since the previous measured day across open software and world events," explicitly contrasted with "raw data." That is far more informative than the bare name 'rising.' It does not, however, differentiate itself from any of the single-word sibling tools (markets, exchanges, platforms, etc.), which all look like data APIs.

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?

Usage context is implied through the route enumeration (/days, /today, /{date}, /history) and the note that this is "a daily answer, not raw data," which nudges the agent away from per-record queries. There is no explicit when-to-use/when-not-to-use guidance and no sibling tool is named as an alternative, so the agent must infer selection from the route list.

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