x402 endpoint observation history (paid)

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

With no annotations, the description carries full burden. It clearly discloses the pay-per-call model, auto-payment behavior, and fallback to price quote. This is critical for agent decision-making and adds value beyond the schema.

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?

Three sentences, each adding distinct value: event types, payment behavior, and window. No redundancy; front-loaded with the tool's primary action.

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?

Given the tool has only 2 parameters and no output schema, the description covers the input, behavior, and response intent. It could be more explicit about the response format (e.g., JSON array), but the listed event types and 'time-series' give adequate context.

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 baseline is 3. The description restates the parameters (resource URL, days) and adds the day range (1-90). It does not add new meaning beyond what the schema provides, but it does clarify that the output contains specific event types.

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 specifies a clear verb ('Raw observation time-series') and resource ('SPECIFIC x402 endpoint'), listing exact event types included (listing/delisting, price changes, payTo changes, probe results) and time window (1-90 days). This distinguishes it from sibling tools like x402_ecosystem_stats which focus on aggregate statistics.

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 implies usage for historical data of a specific endpoint but does not explicitly state when to use or avoid this tool. No guidance on alternatives or when not to use is provided, leaving inference up to the agent.

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