x402 watch — create 30-day endpoint monitor (paid)

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

With no annotations, the description carries full burden and does so thoroughly. It discloses critical behaviors: payTo changes on templated endpoints are severity 'warn' not 'critical', liveness_flapping coalesces alerts, all URLs are connection-tested before payment with no charge for unreachable ones, webhook signature details (HMAC-SHA256 keyed by hex of sha256 secret, not raw secret), and pay-per-call cost. This is exemplary transparency 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?

The description is long due to the tool's complexity, but every sentence adds value: purpose, event semantics, flapping behavior, return URLs, alternatives, URL configuration, signature format, and cost. It is front-loaded with the primary purpose and flows logically. No tautology or 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?

Given the tool's complexity, no annotations, and no output schema, the description is remarkably complete. It explains return artifacts (bearer secret, poll/renew/edit/cancel URLs, next_steps), payment flow, webhook signature construction, event types, and delivery testing. The only minor omission is a detailed list of event types (left to schema), but the description mentions them by name and provides enough for an agent to invoke correctly.

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 baseline is 3. The description adds extra semantics: webhook_url/slack_url accept a single string or an array (max 5), all URLs are connection-tested before payment, and delivery is reported in 'delivery.connection_test'. These details go beyond the schema's property descriptions, enhancing understanding of parameter behavior.

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 opens with a specific verb+resource: 'Start monitoring ONE x402 endpoint for 30 days.' It clearly differentiates from siblings by naming x402_watch_events for polling and mentioning renew/edit/cancel URLs returned on success. The scope (one endpoint, 30 days) and delivered event types are 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?

The description provides clear context on when to use this tool (start a new monitor) and explicitly names an alternative for consuming events: 'Use x402_watch_events to poll the append-only log.' It also describes payment behavior and that URLs are connection-tested before payment, but does not give explicit 'when not to use' exclusions beyond implying this is for creation. This is clear context without a full when-not matrix.

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