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

With no annotations provided, the description carries the full burden and does so excellently. It discloses that the tool is PAID ($25 USDC per call via x402 on Base), explains the two-step payment flow (first call without payment_signature returns payment requirements), reveals that Coinbase's discovery API has no archive and this reconstructs from own snapshots, and explains why wallet-count rather than call-volume ranking is used. This is exceptional behavioral disclosure for a paid, authenticated tool.

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 information-rich, with every sentence carrying new information. It's front-loaded with the core purpose, then details data dimensions, then cost/payment specifics. It's longer than ideal but each fact is decision-relevant, and the payment workflow is critical for an agent to invoke correctly. A tighter rewrite could trim minor redundancies but there's no true waste.

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-param, no-output-schema tool with no annotations, this description is remarkably complete. It covers the full scope of returned data, explains the payment mechanism thoroughly, provides a free alternative endpoint, and gives rationale for why the ranking metric was chosen. The agent can correctly decide whether to invoke, how to handle the payment flow, and what results to expect.

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 the schema already documents all three parameters well. The description adds a bit of context ('Omit for the full archive', 'Max 400' is in schema, domain scoping mentioned) but largely restates what the schema provides. The payment flow two-step process is explained clearly in the schema's payment_signature description, so the description adds marginal value. Baseline 3 is appropriate given full schema coverage.

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 this tool returns the x402 Bazaar as a time series reconstructed from daily snapshots, and enumerates exactly what data dimensions it covers: per-day ecosystem GMV, merchant/listing counts, price-band distribution, median/P90 pricing, per-merchant lifecycle, price changes, and wallet-based movers. It's a specific verb+resource with rich scope that clearly distinguishes it from siblings like get_market_pulse or get_bazaar_category_trends.

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 provides clear context on when to use it (historical/time-series analysis) and explicitly contrasts it with the real-time snapshot view at /state-of-x402. It even explains the rationale behind wallet-count ranking vs call volume, giving the agent decision-relevant guidance. However, it doesn't explicitly name alternative tools or state when NOT to use this tool versus siblings in the tool list.

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