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

Annotations cover the safety profile (readOnly, openWorld, non-idempotent), and the description adds genuinely useful non-obvious context: the data is from the vendor's own daily Bazaar history starting 2026-09-28, and the call costs $0.01 USDC via x402 or prepaid credits, currently in free trial. That billing/provenance detail is exactly what annotations cannot convey.

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-loads the core definition, then audience, then pricing; every sentence carries information and nothing is padded. Slightly dense with three distinct concerns packed into one block, but no wasted words.

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?

An output schema exists so return format needn't be described, and price/provenance are covered. The notable gap is the interaction between the 90-day maximum window and a history that only started 2026-09-28 — the agent isn't told what happens when the requested window exceeds available history, which directly affects parameter choice.

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% and both parameters are documented there with defaults and bounds, so the baseline is 3. The description's phrase 'last N days' restates the days parameter without adding format, edge-case, or interpretation detail beyond the schema.

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?

States a specific verb+resource+ranking metric: services with the biggest rise in unique buyers over the last N days. Distinguishes it from siblings like x402-find (finding services) and x402-recommend (recommending them) by making the growth-over-time signal explicit.

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?

Names an audience ('builders, investors and agents choosing reliable providers') which implies the use case, but never states when to pick this over x402-recommend, x402-find, or x402-find-live, nor any exclusions. Usage is inferable rather than directed.

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