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

With no annotations present, the description carries the full burden and does add real disclosure: it is free, it is a static snapshot rather than a live query, sources are attributed, and pre-launch figures are explicitly labeled illustrative — a data-reliability caveat an agent would otherwise have no way to know. Gaps remain on refresh cadence, caching, and auth, but the provenance and reliability note is substantive.

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 short sentences with no filler. The cost/access fact is front-loaded, the payload contents follow, and the caveat closes it out — every clause carries information.

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?

With no parameters and no output schema, the description must convey the shape of the return value, and it does by listing the data sections. For a zero-arg read tool this is nearly sufficient; only freshness/caching semantics are missing.

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 tool takes zero parameters, so there is nothing for the description to disambiguate; baseline 4 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 names the concrete artifact (market.json) and enumerates its contents — x402 settlement stats, MCP ecosystem size, index coverage, category economics, 30-day movers — so an agent knows exactly what data comes back. It is distinguishable from siblings like get_market_category or get_order_book by being the aggregate snapshot, though that distinction is inferred 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 only usage signal is 'Free.', which tells the agent there is no cost barrier but says nothing about when to call this versus get_market_category, get_pulse, or get_order_book. No prerequisites, no exclusions, no alternative routing.

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